Atrial Fibrillation Ablation in Systolic Dysfunction: Clinical and Echocardiographic Outcomes

Background:Heart failure and atrial fibrillation (AF) often coexist in a deleterious cycle.Objective:To evaluate the clinical and echocardiographic outcomes of patients with ventricular systolic dysfunction and AF treated with radiofrequency (RF) ablation.Methods:Patients with ventricular systolic dysfunction [ejection fraction (EF) <50%] and AF refractory to drug therapy underwent stepwise RF ablation in the same session with pulmonary vein isolation, ablation of AF nests and of residual atrial tachycardia, named "background tachycardia". Clinical (NYHA functional class) and echocardiographic (EF, left atrial diameter) data were compared (McNemar test and t test) before and after ablation.Results:31 patients (6 women, 25 men), aged 37 to 77 years (mean, 59.8±10.6), underwent RF ablation. The etiology was mainly idiopathic (19 p, 61%). During a mean follow-up of 20.3±17 months, 24 patients (77%) were in sinus rhythm, 11 (35%) being on amiodarone. Eight patients (26%) underwent more than one procedure (6 underwent 2 procedures, and 2 underwent 3 procedures). Significant NYHA functional class improvement was observed (pre-ablation: 2.23±0.56; postablation: 1.13±0.35; p<0.0001). The echocardiographic outcome also showed significant ventricular function improvement (EF pre: 44.68%±6.02%, post: 59%±13.2%, p=0.0005) and a significant left atrial diameter reduction (pre: 46.61±7.3 mm; post: 43.59±6.6 mm; p=0.026). No major complications occurred.Conclusion:Our findings suggest that AF ablation in patients with ventricular systolic dysfunction is a safe and highly effective procedure. Arrhythmia control has a great impact on ventricular function recovery and functional class improvement.

Observations on two biological races of Schistosoma mansoni

A comparative study of the BH strain of Schistosoma mansoni from Belo Horizonte, Minas Gerais state, infective to Biomphalaria glabrata from the same locality, and the SJ strain from São José dos Campos, São Paulo state, infective to B. tenagophila from the latter locality, showed the following differences: 1. Length of adult worms and size of eggs significantly larger in the BH strain. 2. Higher infection rates in the B. glabrata-BH strain association than in the B. tenagophila-SJ strain association, following exposure of each snail to 1 or 10 miracidia. 3.Longer prepatent period (from penetration of miracidium to first shedding of cercariae) in the B. tenagophila-SJ strain association. 4. Infection of both Biomphalaria species when exposed to hybrid miracidia from crosses between the two strains, at lower levels than those resulting from exposure of each snail species to miracidia of the pure sympatric strain. (Both Biomphalaria populations are practically refractory to infection with the allopatric strain). These results are interpreted as pointing to a better host-parasite adjustment in the B. glabrata-BH strain association than in the B. tenagophila-SJ association. The interfertility between the two strains, which produced viable hybrids infective to both Biomphalaria species, supports the conclusion that the observed differences are merely intraspecific, and that the two strains may be considered distinct biological races of Schistosoma mansoni.

Potential schistosome-vector snails and associated trematodes in ricefields of Corrients province, Argentina: preliminary results

Considering the possibility of introduction of schistosomiasis mansoni into Argentina as a consequence of dam construction on the Rio De La Plata basin, preliminary studies have been carried out on agrosystems such as ricefields in Corrientes province with the following purposes: 1) to survey and estimate the relative abundance of planorbids and identify potential vector species; 2) to identify environmental factors capable of influencing Biomphalaria population dynamics; and 3) to find out snail-parasite associations and estimate snail infection rates in order to detect possible competitive interactions between larval stages of native trematodes that could be used in biological control of Schistosoma mansoni. Three potential schistosome vectors were detected in ricefields, namely Biomphalaria straminea, B. tenagophila and B. peregrina, although B. orbignyi, a species refractory to infection with S. mansoni, proved the most frequent and abundant. Positive correlations (P<0.05) were found between Biomphalaria abundance and some environmental parameters: conductivity, hardness, calcium, nitrites plus nitrates, ammonium and bicarbonates. Water temperature correlation was negative (P<0.05). No correlation (P>0.05) was found in total iron, phosphates (SRP), pH and soil granulometry. Echinocercariae developed from rediae and belonging to Petasiger sp., Paryphostomum sp., and other undetermined species were found.

The distribution of agglutinins and lytic activity against Trypanosoma rangeli and erythrocytes in Rhodnius prolixus and Triatoma infestans tissue extracts and haemolymph

Haemolymph, heads, salivary glands, crops, midguts, hindguts, and Malpighian tubules from Rhodnius prolixus and Triatoma infestans were extracted in phosphate or Tris buffer saline with calcium, and tested for agglutination and lytic activities by microtitration against both vertebrateerythrocytes and cultured epimatigote forms of Trypanosoma rangeli. Haemagglutination activity against rabbit erythrocytes was found in the crop, midgut and hindgut extracts of T. infestans but only in the haemolymph of R. prolixus. Higher titres of parasite agglutinins were found in R. prolixus haemolymph than T. infestans, whilst the converse occurred for the tissue extracts. In addition, the extracts of T. infestans salivary glands, but not those of R. prolixus, showed a trypanolytic activity that was heat-inactivated and was not abolished by pre-incubation with any of the sugars or glycoproteins tested. T. infestans, which is refractory to infection by T. rangeli, thus appears to contain a much wider distribution of agglutinating and trypanolytic factors in its tissues than the more susceptible species, R. prolixus

Bioactive glycosides from Chinese medicines

Glycosides are the bioactive components of many famous Chinese medicines. Here reported are some bioactive glycosides we discovered from Chinese medicines in recent years. (1) Pheolic glycosides from Chinese medicines: Gastrodia elata, acontium austroynanense and Helicia erratica, three bioactive phenolic glycosides were discovered and two of them have been developed into new drugs. (2) Terpenoidal glycosides: a) Monoterpenoid: the sweroside from Swertia mollensis has been developed intro an anti-hepatitis drug; b) Diterpenoid: Phlomis betonicoides contains sweet glycoides; c) Triterpenoid: many biologically active triterpenoid glycosides were isolated from Panax plants and Siraitia grosvenorii. (3) Steroidal glycosides: a) C21-steroid: Cynanchum otophyllum and C. atratrum contain anti-epilepsy and-tumor glycosides; b) C27-steroid Hemostatic saponins were found in Paris polyphylla.

Benznidazole vs benznidazole in multilamellar liposomes: how different they interact with blood components?

In spite of its widespread use, benznidazole's (BNZ) toxicity and low efficacy remains as major drawbacks that impair successful treatments against Chagas disease. Previously, attempting to increase the selectivity and reduce its toxicity on infected tissues, multilamellar liposomes (MLV) composed of hydrogenated soybean phosphatidylcholine (HSPC): distearoyl-phosphatidylglycerol (DSPG): cholesterol (CHOL) 2:1:2 mol:mol loaded with BNZ (MLV-BNZ) were designed. In this work we compared different properties of MLV-BNZ with those of BNZ. Opposite to other hydrophobic drugs, the results indicated that slight changes of BNZ×s association degree to proteins and lipoproteins should not modify the percentage of unbound drug available to exert pharmacological action. On the other hand, when loaded in MLV, BNZ reduced its association to plasma proteins in 45% and became refractory to the sinking effect of blood, dropping 4.5 folds. Additionally, when loaded in MLV, BNZ had higher volume distribution (160 ± 20 vs 102 ± 15 ml/kg) and total clearance (35.23 ± 2.3 vs 21.9 ± 1.4 ml/h.kg), and lower concentration-time curve (7.23 ± 0.2 vs 9.16 ± 0.5 µg.h/ml) than BNZ. Hence, these studies showed that for MLV-BNZ, the amount of BNZ can be substantially increased, from 25 to 70%, being this formulation more rapidly cleared from circulation than free drug; also due to the lower interaction with blood components, lower side effects can be expected.

Thymus involution in alloxan diabetes: analysis of mast cells

We previously reported that alloxan-induced diabetes results in reduction in the number and reactivity of mast cells at different body sites. In this study, the influence of diabetes on thymic mast cells was investigated. Thymuses from diabetic rats showed marked alterations including shrinkage, thymocyte depletion, and increase in the extracellular matrix network, as compared to those profiles seen in normal animals. Nevertheless, we noted that the number and reactivity of mast cells remained unchanged. These findings indicate that although diabetes leads to critical alterations in the thymus, the local mast cell population is refractory to its effect. This suggests that thymic mast cells are under a different regulation as compared to those located in other tissues.

Evolution and pathology in Chagas disease: a review

Trypanosoma cruzi acute infections often go unperceived, but one third of chronically infected individuals die of Chagas disease, showing diverse manifestations affecting the heart, intestines, and nervous systems. A common denominator of pathology in Chagas disease is the minimal rejection unit, whereby parasite-free target host cells are destroyed by immune system mononuclear effectors cells infiltrates. Another key feature stemming from T. cruzi infection is the integration of kDNA minicircles into the vertebrate host genome; horizontal transfer of the parasite DNA can undergo vertical transmission to the progeny of mammals and birds. kDNA integration-induced mutations can enter multiple loci in diverse chromosomes, generating new genes, pseudo genes and knock-outs, and resulting in genomic shuffling and remodeling over time. As a result of the juxtaposition of kDNA insertions with host open reading frames, novel chimeric products may be generated. Germ line transmission of kDNA-mutations determined the appearance of lesions in birds that are indistinguishable from those seen in Chagas disease patients. The production of tissue lesions showing typical minimal rejection units in birds' refractory to T. cruzi infection is consistent with the hypothesis that autoimmunity, likely triggered by integration-induced phenotypic alterations, plays a major role in the pathogenesis of Chagas disease.

Perspectives in the control of infectious diseases by transgenic mosquitoes in the post-genomic era: a review

Arthropod-borne diseases caused by a variety of microorganisms such as dengue virus and malaria parasites afflict billions of people worldwide imposing major economic and social burdens. Despite many efforts, vaccines against diseases transmitted by mosquitoes, with the exception of yellow fever, are not available. Control of such infectious pathogens is mainly performed by vector management and treatment of affected individuals with drugs. However, the numbers of insecticide-resistant insects and drug-resistant parasites are increasing. Therefore, inspired in recent years by a lot of new data produced by genomics and post-genomics research, several scientific groups have been working on different strategies to control infectious arthropod-borne diseases. This review focuses on recent advances and perspectives towards construction of transgenic mosquitoes refractory to malaria parasites and dengue virus transmission.

Biomphalaria molluscs (Gastropoda: Planorbidae) in Rio Grande do Sul, Brazil

The present study was aimed at characterising Biomphalaria species using both morphological and molecular (PCR-RFLP) approaches. The specimens were collected in 15 localities in 12 municipalities of the southern region of the state of Rio Grande do Sul, Brazil. The following species were found and identified: Biomphalaria tenagophila guaibensis, Biomphalaria oligoza and Biomphalaria peregrina. Specimens of the latter species were experimentally challenged with the LE Schistosoma mansoni strain, which showed to be refractory to infection.

Male accessory gland substances from Aedes albopictus affect the locomotor activity of Aedes aegypti females

Dengue is one of the world’s most important mosquito-borne diseases and is usually transmitted by one of two vector species: Aedes aegypti or Aedes albopictus . These two diurnal mosquitoes are frequently found coexisting in similar habitats, enabling interactions between adults, such as cross-mating. The objective of this study was to assess cross-mating between Ae. aegypti females and Ae. albopictus males under artificial conditions and evaluate the locomotor activity of Ae. aegypti virgin females injected with male accessory gland (MAG) homogenates to infer the physiological and behavioural responses to interspecific mating. After seven days of exposure, 3.3-16% of Ae. aegypti females mated with Ae. albopictus males. Virgin Ae. aegypti females injected with conspecific and heterospecific MAGs showed a general decrease in locomotor activity compared to controls and were refractory to mating with conspecific males. The reduction in diurnal locomotor activity induced by injections of conspecific or heterospecific MAGs is consistent with regulation of female reproductive activities by male substances, which are capable of sterilising female Ae. aegypti through satyrisation by Ae. albopictus .