Evaluation of Toxoplasma gondii placental transmission in BALB/c mice model

Toxoplasma gondii infection is common worldwide and highly important to pregnant women as it can be transmitted to the fetus via the placenta. This study aimed at evaluating the prevention of placental transmission in two different strains after chronic infection with each one of the strains. A BALB/c mice model was inoculated 30 days before breeding (immunization) and re-infected 12 and 15 days after pregnancy (challenge). Seven experimental groups were assayed: G1: ME49-immunization (type II), M7741-challenge (type III); G2: M7741-immunization, ME49-challenge; G3, ME49-immunization; G4: M7741-immunization; G5: ME49-challenge; G6: M7741-challenge; G7: saline solution inoculation. Serology, mouse bioassay, PCR and RLFP of the uterus, placenta and fetus were performed to determine the congenital transmission of the strains challenged after chronic infection. IgG T. gondii antibodies were detected in G1, G2, G3 and G4, but not in G5, G6 and G7. All animals of G5 and G6 were IgM-positive. Congenital infection was not detected by bioassay and PCR. Nonetheless, placentas from G3 and G4 resulted positive but no corresponding fetal infection was detected. G1 and G2 did not show the genotype of the strain challenged during pregnancy, only those of chronic infection. Thus, the chronically infected BALB/c mice showed no re-infection after inoculation with another strain during pregnancy. Further studies with different parasite loads and different mice lineages are needed.     

DNA repair genes XRCC1 and XRCC3 polymorphisms and their relationship with the level of micronuclei in breast cancer patients

Breast cancer (BC) is the most prevalent type worldwide, besides being one of the most common causes of death among women. It has been suggested that sporadic BC is most likely caused by low-penetrance genes, including those involved in DNA repair mechanisms. Furthermore, the accumulation of DNA damage may contribute to breast carcinogenesis. In the present study, the relationship between two DNA repair genes, viz., XRCC1 (Arg399Gln) and XRCC3 (Thr241Met) polymorphisms, and the levels of chromosome damage detected in 65 untreated BC women and 85 healthy controls, was investigated. Chromosome damage was evaluated through micronucleus assaying, and genotypes determined by PCR-RFLP methodology. The results showed no alteration in the risk of BC and DNA damage brought about by either XRCC1 (Arg399Gln) or XRCC3 (Thr241Met) action in either of the two groups. Nevertheless, on evaluating BC risk in women presenting levels of chromosome damage above the mean, the XRCC3Thr241Met polymorphism was found to be more frequent in the BC group than in the control, thereby leading to the conclusion that there is a slight association between XRCC3 (241 C/T) genotypes and BC risk in the subgroups with higher levels of chromosome damage.     

Factors Affecting the Abundance of Leaf-Litter Arthropods in Unburned and Thrice-Burned Seasonally-Dry Amazonian Forests

Fire is frequently used as a land management tool for cattle ranching and annual crops in the Amazon. However, these maintenance fires often escape into surrounding forests, with potentially severe impacts for forest biodiversity. We examined the effect of experimental fires on leaf-litter arthropod abundance in a seasonally-dry forest in the Brazilian Amazon. The study plots (50 ha each) included a thrice-burned forest and an unburned control forest. Pitfall-trap samples were collected at 160 randomly selected points in both plots, with sampling stratified across four intra-annual replicates across the dry and wet seasons, corresponding to 6, 8, 10 and 12 months after the most recent fire. Arthropods were identified to the level of order (separating Formicidae). In order to better understand the processes that determine arthropod abundance in thrice-burned forests, we measured canopy openness, understory density and litter depth. All arthropod taxa were significantly affected by fire and season. In addition, the interactions between burn treatment and season were highly significant for all taxa but Isoptera. The burned plot was characterized by a more open canopy, lower understory density and shallower litter depth. Hierarchical partitioning revealed that canopy openness was the most important factor explaining arthropod order abundances in the thrice-burned plot, whereas all three environmental variables were significant in the unburned control plot. These results reveal the marked impact of recurrent wildfires and seasonality on litter arthropods in this transitional forest, and demonstrate the overwhelming importance of canopy-openness in driving post-fire arthropod abundance.     

Noninvasive methods to determine the critical micelle concentration of some bile acid salts

In this work the critical micelle concentrations (cmc) of four bile salts, sodium cholate, sodium glycocholate, sodium deoxycholate, and sodium glycodeoxycholate, are determined and presented. Three independent noninvasive methodologies (potentiometry, derivative spectrophotometry, and light scattering) were used for cmc determination, at 25 degrees C with ionic strength adjusted to 0.10 M with NaCl. Spectrophotometric and potentiometric studies of some bile salts were also executed at various ionic strength values, thus allowing the influence of the ionic strength on the cmc value of the bile salt to be assessed. A critical comparison of the cmc values obtained with data collected from the literature is presented. Furthermore, this work makes an evaluation of the conceptual bases of different methodologies commonly used for cmc determination, since variations in the results obtained can be related mainly to different intrinsic features of the methods used (such as sensitivity or the need to include tracers or probes) or to the operational cmc definition applied. The undoubted definition of the experimental bile salt concentration that corresponds to cmc (operational cmc) is essential since in the case of these amphiphiles the formation of micelles is not as abrupt as in the case of ordinary association colloids. The biphasic nature of their aggregation leads to a "round-shaped" variation of the experimental parameters under analysis, which makes difficult the evaluation of the cmc values and can be responsible for the different results obtained.     

LOW PROFILE BIOPROSTHESIS FOR CARDIAC VALVE REPLACEMENT: EARLY CLINICAL RESULTS

Between May 1976 and April 1977, 100 patients underwent cardiac valve replacement with a unique low profile glutaraldehyde-treated porcine aortic xenograft. These patients were classified in four groups: Group I, 43 patients who underwent isolated mitral valve replacement (MVR); Group II, 27 patients who had isolated aortic valve replacement (AVR); Group III, 10 patients who had MVR and AVR; and Group IV, 20 patients who had MVR or AVR associated with other cardiac procedures. The operative mortality for Group I was 2.3% (1 of 43) and 15% (3 of 20) in Group IV. The total operative mortality was 4% (4 of 100) and the late mortality was 1.02% (1 of 96 survivors), who died apparently secondary to a cardiac arrhythmia. During a follow-up period extending for 16 months, thromboembolic complications occurred early in the postoperative period in 3% (3 of 100), one patient with neurological residual, and two patients with transient symptoms only. The embolic complications occurred only in Group I. Considering all patients in whom the mitral valves were replaced, the incidence of emboli was 4.9% (3 of 61). The 96 patients did not receive anticoagulant therapy. Reoperation was necessary in one patient because of periprosthetic leak. The incidence of endocarditis was 1.02% (1 of 96 survivors). We recommend anticoagulant therapy for eight to twelve weeks postoperatively in MVR patients after bioprosthetic insertion.     

Synthesis and preliminary biological evaluation of a compound library of triazolylcyclitols

A small library of compounds was prepared by a combination of toluene dioxygenase (TDO)-catalyzed enzymatic dihydroxylation and copper(I)-catalyzed Hüisgen cycloaddition. Some compounds were obtained by coupling an alkyne and a conduritol derivative, while more complex structures were obtained by a double Hüisgen reaction of a dialkyne and two molecules of the cyclitol. The compounds were fully characterized and subjected to preliminary biological screening.     

Characterization of hypoglycemiant plants by total reflection X-ray fluorescence spectrometry

In this work, synchrotron radiation total reflection X-ray fluorescence spectrometry (SRTXRF) was used to determine trace elements in eight hypoglycemiant plants (Trigonella foenum graecum, Panax ginseng, Pfaffia paniculata, Myrcia speciosa, Zea mays, Harpagophytum procumbens, Syzygium jambolona, and Bauhinia forficate). The elements P, K, Ca, Ti, Mn, Fe, Cu, Zn, Rb, and Sr were detected in all medicinal plants investigated, whereas Si, S, Sc, V, Cr, Co, Ni, Se, Nb, Mo, Sn, Sb, Ba, Hg, and Pb were detected only in some of the samples. The concentration of elements in hypoglycemiant plants varied from 0.15 μg/g of Co to 3.0×10⁴ μg/g of K and the mean of experimental limit of detection for these elements were 0.14 and 3.6 μg/g, respectively.     

Costly Inheritance and the Persistence of Insecticide Resistance in Aedes aegypti Populations

Global emergence of arboviruses is a growing public health concern, since most of these diseases have no vaccine or prevention treatment available. In this scenario, vector control through the use of chemical insecticides is one of the most important prevention tools. Nevertheless, their effectiveness has been increasingly compromised by the development of strong resistance observed in field populations, even in spite of fitness costs usually associated to resistance. Using a stage-structured deterministic model parametrised for the Aedes aegypti—the main vector for dengue—we investigated the persistence of resistance by studying the time for a population which displays resistance to insecticide to revert to a susceptible population. By means of a comprehensive series of in-silico experiments, we studied this reversal time as a function of fitness costs and the initial presence of the resistance allele in the population. The resulting map provides both a guiding and a surveillance tool for public health officers to address the resistance situation of field populations. Application to field data from Brazil indicates that reversal can take, in some cases, decades even if fitness costs are not small. As by-products of this investigation, we were able to fit very simple formulas to the reversal times as a function of either cost or initial presence of the resistance allele. In addition, the in-silico experiments also showed that density dependent regulation plays an important role in the dynamics, slowing down the reversal process.     

Profiles of Steroid Hormones in Canine X-Linked Muscular Dystrophy via Stable Isotope Dilution LC-MS/MS

Golden retriever muscular dystrophy (GRMD) provides the best animal model for characterizing the disease progress of the human disorder, Duchenne muscular dystrophy (DMD). The purpose of this study was to determine steroid hormone concentration profiles in healthy golden retriever dogs (control group - CtGR) versus GRMD-gene carrier (CaGR) and affected female dogs (AfCR). Therefore, a sensitive and specific analytical method was developed and validated to determine the estradiol, progesterone, cortisol, and testosterone levels in the canine serum by isotope dilution liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). To more accurately understand the dynamic nature of the serum steroid profile, the fluctuating levels of these four steroid hormones over the estrous cycle were compared across the three experimental groups using a multivariate statistical analysis. The concentration profiles of estradiol, cortisol, progesterone, and testosterone revealed a characteristic pattern for each studied group at each specific estrous phase. Additionally, several important changes in the serum concentrations of cortisol and estradiol in the CaGR and AfCR groups seem to be correlated with the status and progression of the muscular dystrophy. A comprehensive and quantitative monitoring of steroid profiles throughout the estrous cycle of normal and GRMD dogs were achieved. Significant differences in these profiles were observed between GRMD and healthy animals, most notably for estradiol. These findings contribute to a better understanding of both dog reproduction and the muscular dystrophy pathology. Our data open new venues for hormonal behavior studies in dystrophinopathies and that may affect the quality of life of DMD patients.