Predictors of Arrhythmic Events Detected by Implantable Loop Recorders in Renal Transplant Candidates

AbstractBackground:The recording of arrhythmic events (AE) in renal transplant candidates (RTCs) undergoing dialysis is limited by conventional electrocardiography. However, continuous cardiac rhythm monitoring seems to be more appropriate due to automatic detection of arrhythmia, but this method has not been used.Objective:We aimed to investigate the incidence and predictors of AE in RTCs using an implantable loop recorder (ILR).Methods:A prospective observational study conducted from June 2009 to January 2011 included 100 consecutive ambulatory RTCs who underwent ILR and were followed-up for at least 1 year. Multivariate logistic regression was applied to define predictors of AE.Results:During a mean follow-up of 424 ± 127 days, AE could be detected in 98% of patients, and 92% had more than one type of arrhythmia, with most considered potentially not serious. Sustained atrial tachycardia and atrial fibrillation occurred in 7% and 13% of patients, respectively, and bradyarrhythmia and non-sustained or sustained ventricular tachycardia (VT) occurred in 25% and 57%, respectively. There were 18 deaths, of which 7 were sudden cardiac events: 3 bradyarrhythmias, 1 ventricular fibrillation, 1 myocardial infarction, and 2 undetermined. The presence of a long QTc (odds ratio [OR] = 7.28; 95% confidence interval [CI], 2.01–26.35; p = 0.002), and the duration of the PR interval (OR = 1.05; 95% CI, 1.02–1.08; p < 0.001) were independently associated with bradyarrhythmias. Left ventricular dilatation (LVD) was independently associated with non-sustained VT (OR = 2.83; 95% CI, 1.01–7.96; p = 0.041).Conclusions:In medium-term follow-up of RTCs, ILR helped detect a high incidence of AE, most of which did not have clinical relevance. The PR interval and presence of long QTc were predictive of bradyarrhythmias, whereas LVD was predictive of non-sustained VT.

Echocardiographic Predictors of Worse Outcome After Cardiac Resynchronization Therapy

Abstract Background: Cardiac resynchronization therapy (CRT) is the recommended treatment by leading global guidelines. However, 30%-40% of selected patients are non-responders. Objective: To develop an echocardiographic model to predict cardiac death or transplantation (Tx) 1 year after CRT. Method: Observational, prospective study, with the inclusion of 116 patients, aged 64.89 ± 11.18 years, 69.8% male, 68,1% in NYHA FC III and 31,9% in FC IV, 71.55% with left bundle-branch block, and median ejection fraction (EF) of 29%. Evaluations were made in the pre‑implantation period and 6-12 months after that, and correlated with cardiac mortality/Tx at the end of follow-up. Cox and logistic regression analyses were performed with ROC and Kaplan-Meier curves. The model was internally validated by bootstrapping. Results: There were 29 (25%) deaths/Tx during follow-up of 34.09 ± 17.9 months. Cardiac mortality/Tx was 16.3%. In the multivariate Cox model, EF < 30%, grade III/IV diastolic dysfunction and grade III mitral regurgitation at 6‑12 months were independently related to increased cardiac mortality or Tx, with hazard ratios of 3.1, 4.63 and 7.11, respectively. The area under the ROC curve was 0.78. Conclusion: EF lower than 30%, severe diastolic dysfunction and severe mitral regurgitation indicate poor prognosis 1 year after CRT. The combination of two of those variables indicate the need for other treatment options.

Prognostic Value of Pulmonary Vascular Resistance by Magnetic Resonance in Systolic Heart Failure

Abstract Background: Pulmonary hypertension is associated with poor prognosis in heart failure. However, non-invasive diagnosis is still challenging in clinical practice. Objective: We sought to assess the prognostic utility of non-invasive estimation of pulmonary vascular resistances (PVR) by cardiovascular magnetic resonance to predict adverse cardiovascular outcomes in heart failure with reduced ejection fraction (HFrEF). Methods: Prospective registry of patients with left ventricular ejection fraction (LVEF) < 40% and recently admitted for decompensated heart failure during three years. PVRwere calculated based on right ventricular ejection fraction and average velocity of the pulmonary artery estimated during cardiac magnetic resonance. Readmission for heart failure and all-cause mortality were considered as adverse events at follow-up. Results: 105 patients (average LVEF 26.0 ±7.7%, ischemic etiology 43%) were included. Patients with adverse events at long-term follow-up had higher values of PVR (6.93 ± 1.9 vs. 4.6 ± 1.7estimated Wood Units (eWu), p < 0.001). In multivariate Cox regression analysis, PVR ≥ 5 eWu(cutoff value according to ROC curve) was independently associated with increased risk of adverse events at 9 months follow-up (HR2.98; 95% CI 1.12-7.88; p < 0.03). Conclusions: In patients with HFrEF, the presence of PVR ≥ 5.0 Wu is associated with significantly worse clinical outcome at follow-up. Non-invasive estimation of PVR by cardiac magnetic resonance might be useful for risk stratification in HFrEF, irrespective of etiology, presence of late gadolinium enhancement or LVEF.

Habitat use by a tree frog species of Scinax (Amphibia, Hylidae) at an urban forest fragment from south-eastern Brazil

We studied the pattern of habitat use by the tree frog Scinax aff. perereca. Fieldworks were performed from August 1996 to August 1997 at Parque das Mangabeiras, Belo Horizonte, State of Minas Gerais, southeastern Brazil. Calling males were observed in September, October and December 1996, February to April and June 1997. Females were found only in October 1996. Specimens were found perched on vegetation, on the ground or on stones near waterfall. At Parque das Mangabeiras, S. aff. perereca occupied nine types of substrata. The most frequently used substrata were shrubs, stones at the stream edges, and fallen trunks. The pattern of spatial occupation varied among months. Males were found calling in aggregations on the vegetation and spatial niche breadth was related to species abundance.

Use of tree species by White-throated treerunner (Pygarrhichas albogularis King) in a secondary native forest of southern Chile

ABSTRACT In forest ecosystems, numerous species of insectivorous birds use certain tree species as feeding and nesting substrates. Between 2009 and 2010, the use of different floristic components as feeding substrate by the Pygarrhichas albogularis King, 1831 was evaluated in a southern Chilean secondary native forest. From a total of 13 trees and bush species, six tree species were used by P. albogularis as a feeding substrate. Tree use was limited to intermediate heights (11-20 m) and, mainly, to the trunk (40% of observations) and secondary branches (26%). Pygarrhichas albogularis showed a disproportionated use of N. dombeyi and an important use of trees with a greater age structure (DBH 81-100 cm). Nothofagus dombeyi presented a significantly greater tree bark crevice depth than E. cordifolia. In turn, covariance between crevice depth and invertebrate supply in tree bark was positive and significant. We consider bark depth and invertebrate supply to be the proximate causes explaining P. albogularis disproportionated use of Nothofagus dombeyi.

Morphological aspects of the myocarditis and myositis in Calomys callosus experimentally infected with Trypanosoma cruzi: fibrogenesis and spontaneous regression of fibrosis

Calomys callosus a wild rodent, is a natural host of Trypanosoma cruzi. Twelve C. callosus were infected with 10(5) trypomastigotes of the F strain (a myotropic strain) of T. cruzi. Parasitemia decreased on the 21 st day becoming negative around the 40th day of infection. All animals survived but had positive parasitological tests, until the end of the experiment. The infected animals developed severe inflammation in the myocardium and skeletal muscle. This process was pronounced from the 26 th to the 30th day and gradually subsided from the 50 th day becoming absent or residual on the 64 th day after infection. Collagen was identified by the picro Sirius red method. Fibrogenesis developed early, but regression of fibrosis occurred between the 50th and 64th day. Ultrastructural study disclosed a predominance of macrophages and fibroblasts in the inflammatory infiltrates, with small numbers of lymphocytes. Macrophages had active phagocytosis and showed points of contact with altered muscle cells. Different degrees of matrix expansion were present, with granular and fibrilar deposits and collagen bundles. These alterations subsided by the 64th days. Macrophages seem to be the main immune effector cell in the C. callosus model of infection with T. cruzi. The mechanisms involved in the rapid fibrogenesis and its regression deserve further investigation.

Schellackia (Apicomplexa: Eimeriidae) of the brazilian tree-frog, Phrynohyas venulosa (Amphibia: Anura) from Amazonian Brazil

Endogenous stages of a Schellackia species are described in histological sections of the intestine of the tree-frog, Phrynohyas venulosa, from North Brazil. Most oocysts sporulate within the epithelial cells of the gut, but a few were detected in the lamina propria.

An erythrocytic virus of the brazilian tree-frog, Phrynohyas venulosa

Blood erythrocytes of Brazilian tree-frogs, Phrynohyas venulosa were found to frequently contain single, small, densely staining inclusions. Electron microscopy showed these to be icosahedral viral particles which measured from 250-280 nm in diameter; they were devoid of an envelope, and thus differed from previously described viruses of frog erythrocytes. The infected erythrocytes lacked a crystalline body.

Epidemiological Characteristics of Schistosoma mansoni Infection in Rural and Urban Endemic Areas of Minas Gerais, Brazil

To compare the epidemiological profile and socioeconomic factors associated to the infection by Schistosoma mansoni in a rural and an urban endemic area a cross-sectional study was performed in Água Branca de Minas (rural area) and Bela Fama (urban area), both situated in the State of Minas Gerais, Brazil. Two hundred and eighty eight individuals were surveyed in the rural area and 787 in the urban area. Water contact and socioeconomic questionnaires were used to identify risk factors for the infection. The prevalences of 38.8% and 9.7% and the geometric mean of eggs per gram of faeces of 117.8 and 62.3 were found in the rural and urban areas, respectively. By multivariate statistical analysis age groups over nine years old and previous specific treatment were associated with the infection in rural area. In urban area age over nine years old, low quality housing, weekly fishing and swimming were associated after adjustment by logistic regression

Characterization of Endotrypanum (Kinetoplastida: Trypanosomatidae), a Unique Parasite Infecting the Neotropical Tree Sloths (Edentata)

This article reviews current concepts of the biology of Endotrypanum spp. Data summarized here on parasite classification and taxonomic divergence found among these haemoflagellates come from our studies of molecular characterization of Endotrypanum stocks (representing an heterogenous population of reference strains and isolates from the Brazilian Amazon region) and from scientific literature. Using numerical zymotaxonomy we have demonstrated genetic diversity among these parasites. The molecular trees obtained revealed that there are, at least, three groups (distinct species?) of Endotrypanum, which are distributed in Central and South America. In concordance with this classification of the parasites there are further newer molecular data obtained using distinct markers. Moreover, comparative studies (based on the molecular genetics of the organisms) have shown the phylogenetic relationships between some Endotrypanum and related kinetoplastid lineages.

Distribution of Sandflies (Diptera:Psychodidae) on Tree-trunks in a Non-flooded Area of the Ducke Forest Reserve, Manaus, AM, Brazil

Sandflies were collected in the base of tree-trunks in the seasons of high and least rainfall in the Ducke Forest Reserve, near Manaus in the State of Amazonas. Lutzomyia umbratilis was the most abundant sandfly species. Caryocar villosum, Chrysophyllum amazonicum, Dinizia excelsa, Eschweilera atropetiolata and Parkia multijuga were the tree species on which most sandflies were collected and relative abundance were related to trunk characteristics. Seasonal patterns of sandfly distribution in the forest were observed.

Analysis and estimative of schistosomiasis prevalence for the state of Minas Gerais, Brazil, using multiple regression with social and environmental spatial data

The aim of this work is to establish a relationship between schistosomiasis prevalence and social-environmental variables, in the state of Minas Gerais, Brazil, through multiple linear regression. The final regression model was established, after a variables selection phase, with a set of spatial variables which contains the summer minimum temperature, human development index, and vegetation type variables. Based on this model, a schistosomiasis risk map was built for Minas Gerais.

Remodeling of hepatic vascular changes after specific chemotherapy of schistosomal periportal fibrosis

Hepatosplenic schistosomiasis was the first human disease in which the possibility of extensive long standing hepatic fibrosis being degraded and removed has been demonstrated. When such changes occurred, the main signs of portal hypertension (splenomegaly, esophageal varices) progressively disappeared, implying that a profound vascular remodeling was concomitantly occurring. Hepatic vascular alterations associated with advanced schistosomiasis have already been investigated. Obstruction of the intrahepatic portal vein branches, plus marked angiogenesis and compensatory hyperplasia and hypertrophy of the arterial tree are the main changes present. However, there are no data revealing how these vascular changes behave during the process of fibrosis regression. Here the mouse model of pipestem fibrosis was used in an investigation about these vascular alterations during the course of the infection, and also after treatment and cure of the disease. Animals representing the two polar hepatic forms of the infection were included: (1) "isolated granulomas" characterized by isolated periovular granulomas sparsely distributed throughout the hepatica parenchyma; and (2) 'pipestem fibrosis' with periovular granulomas and fibrosis being concentrated within portal spaces, before and after treatment, were studied by means of histological and vascular injection-corrosion techniques. Instances of widespread portal vein obstruction of several types were commonly found in the livers of the untreated animals. These obstructive lesions were soon repaired, and completely disappeared four months following specific treatment of schistosomiasis. Treatment was accomplished by the simultaneous administration of praziquantel and oxamniquine. The most impressive results were revealed by the technique of injection of colored masses into the portal system, followed by corrosion in strong acid. The vascular lesions of non-treated pipestem fibrosis were represented in the plastic casts by considerable diminution of the fine peripheral portal vein radicles, plus dilatation of periportal collaterals. Four months after treatment, this last picture appeared replaced by tufts of newly interwoven vessels formed along the main portal vein branches, disclosing a strong angiomatoid reparative change. Understanding about the cellular elements at play during fibro-vascular repairing changes of hepatic schistosomiais represents a matter of considerable scientific and conceptual importance. At present time one may only speculate about the participation of some type of natural stem-cell capable of restoring the diseased liver back to normal once the cause of the disorder has been eliminated.

Effects of timber harvest on phlebotomine sand flies (Diptera: Psychodidae) in a production forest: abundance of species on tree trunks and prevalence of trypanosomatids

The Amazon forest is being exploited for timber production. The harvest removes trees, used by sand flies as resting sites, and decreases the canopy, used as refuges by some hosts. The present study evaluated the impact of the timber harvest, the abundance of sand flies, and their trypanosomatid infection rates before and after selective logging. The study was accomplished in terra-firme production forest in an area of timber harvest, state of Amazonas, Brazil. Sand fly catches were carried out in three areas: one before and after the timber harvest, and two control areas, a nature preservation area and a previously exploited area. The flies were caught by aspiration on tree trunks. Samples of sand flies were dissected for parasitological examination. In the site that suffered a harvest, a larger number of individuals was caught before the selective extraction of timber, showing significant difference in relation to the number of individuals and their flagellate infection rates after the logging. The other two areas did not show differences among their sand fly populations. This fact is suggestive of a fauna sensitive to the environmental alterations associated with selective logging.

Antibacterial and antifungal activity of extracts and exudates of the Amazonian medicinal tree Himatanthus articulatus (Vahl) Woodson (common name: sucuba)

Himatanthus articulatus (Vahl) Woodson is a tree found in the northern Amazon savannahs (common name: sucuba) that is used in local Amerindian medicine. Leaf, bark and branch wood methanol extracts, sequentially obtained hexane, ethyl acetate and methanol extracts and latex were evaluated for antifungal and antibacterial activities against American Type Culture Collection (ATCC) and local clinical strains using the disc diffusion method. Methanol extracts and latex inhibited Candida albicans, leaf methanol extracts inhibited Staphylococcus aureus and Bacillus subtilis and bark methanol extracts inhibited B. subtilis. Active extracts inhibited the ATCC and clinical strains. Polar antifungal and antibacterial principles in latex and extracts are thought to be responsible for the inhibition.