Viral causes of cardiac inflammation

Over the past year there have been few significant breakthroughs in the understanding of the etiologies of viral myocarditis or dilated cardiomyopathy (DCM). One interesting trend has been the increasing number of reports of myocarditis associated with parvovirus B19 infection. Whether this is simply a result of improved diagnostics, or reflects an underlying change in the etiology is unclear. However, studies of the underlying mechanisms of these disorders have resulted in several reports linking the acquired and viral forms. Over the past few years the cytoarchitecture has been a focus of study for familial DCM. During the last year, one key molecule, dystrophin, has been shown to be disrupted in patients with end-stage cardiomyopathy, irrespective or etiology, mutated in patients with sporadic forms of disease and identified as a potential susceptibility gene for viral infection of the myocardium. The shared cellular receptor, the Coxsackievirus B-Adenovirus receptor (CAR), for the two most common viral agents associated with acquired myocarditis and DCM, was shown to be up-regulated in patients with DCM, potentially making the expression of this protein a marker of susceptibility to virus infection. However, a study of the CAR gene in patients with DCM or myocarditis did not identify any genetic mutations in these patients. Finally a receptor for viral double stranded RNA (TLR-3) was identified. The role of this receptor in the innate immune response against cardiotropic viruses has yet to be elucidated.     

Cardiac thrombosis and thromboembolism in chronic chagas' heart disease

A retrospective study of Chagas' heart disease was carried out by a review of 1,345 autopsy reports, with special reference to cardiac thrombus and thromboembolic phenomena. The incidence of cardiac thrombus was higher in cases of heart failure (36%) than in cases of sudden death (15%), higher in heavier hearts, and unrelated to age or sex. The left- and right-sided cardiac chambers were equally affected by thrombus. Endocarditis and blood stasis were considered important factors in the pathogenesis of cardiac thrombus. Thromboembolic phenomena were more common in the systemic circulation but caused relatively more deaths by pulmonary embolism. Fourteen percent of patients with thromboembolic phenomena died from them. Patients with multiple thromboembolic phenomena had a higher risk of death from embolism. Cardiac thrombosis or thromboembolic phenomena, or both, were present in 44% of the cases studied. Prophylactic measures should be taken for these important complications of Chagas' heart disease.     

A comparison between the force of infection estimates for blood-borne viruses in injecting drug user populations across the European Union: a modelling study

A number of studies have been conducted in injecting drug user (IDU) populations in Europe, in which the prevalence of human immunodeficiency virus (HIV), hepatitis B virus (HBV) and hepatitis C virus (HCV) was measured together with demographic and epidemiological information such as age and the age at first injection. A measure of the risk of becoming infected is the force of infection (FOI), defined as the per capita rate at which susceptible individuals acquire infection. The objective of this study was to estimate the FOI and its heterogeneity for HBV, HCV and HIV (where available) for IDU populations in a number of countries in Europe. Data were obtained from five countries: Belgium, the United Kingdom, Spain and Italy, and the Czech Republic, which provided two data sets. The model describes the prevalence of infection as a function of the FOI that may vary over time or duration of IDU. In addition to this, if two or more infections were being considered then a parameter describing the potential heterogeneity of the FOI within the IDU population was also estimated. The results here add to the growing evidence that new initiates to injecting are at an increased risk of blood-borne viral infection compared with more experienced IDUs. In addition, there is evidence of individual heterogeneity of FOI estimates within the overall IDU populations. This suggests that different proportions of individuals in each population are at increased risk of infection compared with the rest of the population. Future interventions should identify and target these individuals. Moreover, changes over time in individual heterogeneity estimates of IDU populations may provide an indicator for measuring intervention impacts.     

The affinity of the lectins Ricinus communis and Glycine maxima to carbohydrates on the cell surface of various forms of Trypanosoma cruzi and Trypanosoma rangeli, and the application of these lectins for the identification of T. cruzi in the feces of Rhodnius prolixus

Flagellates of Trypanosoma cruzi (stock Molino 1), obtained from the intestine of experimentally infected Rhodnius prolixus, grown in cellular or acellular culture, as well as from the blood of infected mice, were examined by a direct fluorescence test using the lectins RCA (Ricinus communis-120) and SBA (soy bean agglutinin; Glycine maxima), conjugated with fluorescein isothiocyanate, for the detection of beta-D-galactose and alpha,beta-N-acetyl-D-galactosamine on the membranes of the flagellates. The same reactions were carried out using Trypanosoma rangeli (stock San Agustin), obtained from the intestine, hemo-lymph or salivary glands of experimentally infected R. prolixus, as well as from cultures and from the blood of experimentally infected CFW mice. The results indicate that the membrane of T. rangeli in the salivary glands of the vector contains beta-D-galactose, but that this sugar is absent from all other developmental stages of this trypanosome. All stages of intestinal and cultured. T. cruzi presented positive reactions with RCA-FITC and SBA-FITC. The high specificity of this technique makes it useful for the examination of R. prolixus, previously used in xenodiagnosis of Chagas' disease and for the examination of intradomiciliary or sylvatic vectors in epidemiological surveys in areas where T. cruzi and T. rangeli coexist. Formaldehyde fixed samples can be examined months later and false reports due to T. rangeli can be avoided.