B-Cell Responses in Chronic Chagas Disease: Waning of Trypanosoma cruzi-Specific Antibody-Secreting Cells Following Successful Etiological Treatment

BACKGROUND

A drawback in the treatment of chronic Chagas disease (American trypanosomiasis) is the long time required to achieve complete loss of serological reactivity, the standard for determining treatment efficacy.

METHODS

Antibody-secreting cells and memory B cells specific for Trypanosoma cruzi and their degree of differentiation were evaluated in adult and pediatric study participants with chronic Chagas disease before and after etiological treatment.

RESULTS

T. cruzi-specific antibody-secreting cells disappeared from the circulation in benznidazole or nifurtimox-treated participants with declining parasite-specific antibody levels after treatment, whereas B cells in most participants with unaltered antibody levels were low before treatment and did not change after treatment. The timing of the decay in parasite-specific antibody-secreting B cells was similar to that in parasite-specific antibodies, as measured by a Luminex-based assay, but preceded the decay in antibody levels detected by conventional serology. The phenotype of total B cells returned to a noninfection profile after successful treatment.

CONCLUSIONS

T. cruzi-specific antibodies in the circulation of chronically T. cruzi-infected study participants likely derive from both antigen-driven plasmablasts, which disappear after successful treatment, and long-lived plasma cells, which persist and account for the low frequency and long course to complete seronegative conversion in successfully treated participants.

Immune exhaustion in chronic Chagas disease: Pro-inflammatory and immunomodulatory action of IL-27 in vitro

In chronic Chagas disease, Trypanosoma cruzi-specific T-cell function decreases over time, and alterations in the homeostatic IL-7/IL-7R axis are evident, consistent with a process of immune exhaustion. IL-27 is an important immunoregulatory cytokine that shares T-cell signaling with IL-7 and other cytokines of the IL-12 family and might be involved in the transcriptional regulation of T-cell function. Here, we evaluated the expression and function of IL-27R in antigen-experienced T cells from subjects with chronic Chagas disease and assessed whether in vitro treatment with IL-27 and IL-7 might improve T. cruzi-specific polyfunctional T-cell responses. In vitro exposure of PBMCs to T. cruzi induced a downregulation of IL-27R in CD4+ T cells and an upregulation in CD8+ T cells in subjects without heart disease, while IL-27R expression remained unaltered in subjects with more severe clinical stages. The modulation of IL-27R was associated with functional signaling through STAT3 and STAT5 and induction of the downstream genes TBX21, EOMES and CXCL9 in response to IL-27. In vitro treatment of PBMCs with IL-27 and IL-7 improved monofunctional and polyfunctional Th1 responses, accompanied by the induction of IL-10 and Bcl-2 expression in subjects without heart disease but did not improve those in subjects with cardiomyopathy. Our findings support the process of desensitization of the IL-27/IL-27R pathway along with disease severity and that the pro-inflammatory and immunomodulatory mechanisms of IL-27 might be interconnected.

Impaired frequencies and function of platelets and tissue remodeling in chronic Chagas disease

Chronic inflammation, as a consequence of the persistent infection with Trypanosoma cruzi, leads to continuous activation of the immune system in patients with chronic Chagas disease. We have previously shown that increased sera levels of soluble P-selectin are associated with the severity of the cardiomyopathy distinctive of chronic Chagas disease. In this study, we explored the expression of biomarkers of platelet and endothelial activation, tissue remodeling, and mediators of the coagulation cascade in patients at different clinical stages of chronic Chagas heart disease. The frequencies of activated platelets, measured by the expression of CD41a and CD62P were decreased in patients with chronic Chagas disease compared with those in uninfected subjects, with an inverse association with disease severity. Platelet activation in response to adenosine diphosphate was also decreased in T. cruzi-infected subjects. A major proportion of T. cruzi infected subjects showed increased serum levels of fibrinogen. Patients with severe cardiac dysfunction showed increased levels of endothelin-1 and normal values of procollagen I. In conclusion, chronic infection with T. cruzi induced hemostatic alterations, even in those patients who do not yet present cardiac symptoms.

Polyfunctional CD4+ T cells specific for Trypanosoma cruzi can be restored after in vitro treatment with IL-7 and IL-27

Chronically Trypanosoma cruzi-infected subjects bear several features associated with immune exhaustion, including an impairment in the polyfunctionality of T cells over time and alterations in the IL-7/IL-7R and IL-27/IL-27R axis. Since IL-7 and IL-27 have several functions on different immune cells, gene expression analysis was conducted in total PBMCs in response to rhIL-7 and rhIL-27 in vitro. TBX21, EOMES, GZMB and MIG-cytokine-induced gene expression was low in patients with severe Chagas disease compared with those without cardiac involvement. IL-7-induced TBX21 expression positively correlated with the magnitude of T. cruzi-specific T-cell responses. We also assessed whether treatment of PBMCs of chronically T. cruzi infected subjects with IL-7/IL-27 could improve the quality of T. cruzi-specific T-cell responses. Polyfunctionality of CD4+ T cells was improved after treatment with IL-7 and IL-27, by increasing the production of IL-2 on CD4+ T cells producing two or three functions in response to T. cruzi antigens in patients with mild cardiac disease. These findings support that alterations in IL-7/IL-27 pathways in chronic Chagas disease are not only at the signal-transduction level but also at the transcriptional regulation level. In vitro treatment of PBMCs of patients in early clinical stages of chronic Chagas disease can restore T-cell function.

Trypanosoma cruzi-specific IFN-γ-producing cells in chronic Chagas disease associate with a functional IL-7/IL-7R axis

Background

The severity of cardiac disease in chronic Chagas disease patients is associated with different features of T-cell exhaustion. Here, we assessed whether the ability of T cells to secrete IFN-γ in response to T. cruzi was linked to disruption in immune homeostasis and inflammation in patients with chronic Chagas disease.

Methodology/Principal findings

PBMCs from chronic Chagas disease patients and uninfected controls were examined for frequencies of T. cruzi-responsive IFN-γ-producing cells by ELISPOT and cellular expression and function of IL-7R using flow cytometry. Serum levels of IL-7, IL-21, IL-27, soluble IL-7R, and inflammatory cytokines were also evaluated by ELISA or CBA techniques. Patients possessing T. cruzi-specific IFN-γ-producing cells (i.e. IFN-γ producers) had higher levels of memory T cells capable of modulating the alpha chain of IL-7R and an efficient response to IL-7 compared to that in patients lacking (i.e. IFN-γ nonproducers) parasite-specific T-cell responses. IFN-γ producers also showed low levels of soluble IL-7R, high basal expression of Bcl-2 in T cells and low basal frequencies of activated CD25⁺ T cells. Modulation of IL-7R was inversely associated with serum IL-6 levels and positively associated with serum IL-8 levels. Circulating IL-21 and IL-27 levels were not associated with the frequency of IFN-γ producing cells but were reduced in less severe clinical forms of the disease. In vitro stimulation of PBMCs with IL-7 or IL-27 enhanced IFN-γ production in IFN-γ producers but not in IFN-γ nonproducers.

Conclusions/Significance

Alterations of the IL-7/IL-7R axis and in the levels of inflammatory cytokines were linked to impaired T. cruzi-specific IFN-γ production. These alterations might be responsible of the process of immune exhaustion observed in chronic Chagas disease.

Mechanisms of acquired immune response against Trypanosoma cruzi antigens include both humoral and cellular components that might be critical in a chronic infection. Through a vast number of studies, several groups have postulated that, similar to other chronic infections, T-cell responses in chronic Trypanosoma cruzi infection are driven to exhaustion. Alterations in T-cell signaling pathways have emerged as one of the mechanisms of immune exhaustion. Here, we investigated whether the ability of T cells to secrete IFN-γ in response to T. cruzi was linked to the expression and function of the IL-7 receptor and the cytokines involved in regulating this axis in patients with different clinical forms of chronic Chagas disease. This study showed that the ability of T cells to secrete IFN-γ in response to T. cruzi is linked to an efficient modulation and function of IL-7R and low levels of inflammatory cytokines. Low IFN-γ-ELISPOT responses could not be reverted by in vitro treatment with IL-7. These findings contribute to our understanding of the long-term consequences of T. cruzi-infection and might be useful to delineate novel therapeutic strategies.

Distinct monocyte subset phenotypes in patients with different clinical forms of chronic Chagas disease and seronegative dilated cardiomyopathy

Background

Chronic infection with Trypanosoma cruzi leads to a constant stimulation of the host immune system. Monocytes, which are recruited in response to inflammatory signals, are divided into classical CD14^hiCD16^—, non-classical CD14^loCD16⁺ and intermediate CD14^hiCD16⁺ subsets. In this study, we evaluated the frequencies of monocyte subsets in the different clinical stages of chronic Chagas disease in comparison with the monocyte profile of seronegative heart failure subjects and seronegative healthy controls. The effect of the anti-parasite drug therapy benznidazole on monocyte subsets was also explored.

Methodology/Principal findings

The frequencies of the different monocyte subsets and their phenotypes were measured by flow cytometry. Trypanosoma cruzi-specific antibodies were quantified by conventional serological tests. T. cruzi-infected subjects with mild or no signs of cardiac disease and patients suffering from dilated cardiomyopathy unrelated to T. cruzi infection showed increased levels of non-classical CD14^loCD16⁺ monocytes compared with healthy controls. In contrast, the monocyte profile in T. cruzi-infected subjects with severe cardiomyopathy was skewed towards the classical and intermediate subsets. After benznidazole treatment, non-classical monocytes CD14^loCD16⁺ decreased while classical monocytes CD14^hiCD16^—increased.

Conclusions/Significance

The different clinical stages of chronic Chagas disease display distinct monocyte profiles that are restored after anti-parasite drug therapy. T. cruzi-infected subjects with severe cardiac disease displayed a profile of monocytes subsets suggestive of a more pronounced inflammatory environment compared with subjects suffering from heart failure not related to T. cruzi infection, supporting that parasite persistence might also alter cell components of the innate immune system.

Monocytes are key players during infection, and they leave the bloodstream and migrate into tissues in response to inflammatory signals. Although the recruitment of monocytes is essential for the effective control and clearance of microorganisms, they can also be highly damaging to neighboring tissues. Based on the expression of CD14 and CD16, monocytes are classified into classical, non-classical and intermediate subsets, all of which exert different functions. Because chronic T. cruzi infection induces a constant activation of the host immune system, inflammatory signals are exacerbated, possibly leading to alterations in the frequencies of monocyte subsets. In this study, we evaluated the monocyte profile in Trypanosoma cruzi-infected subjects with different degrees of cardiac dysfunction and explored whether this profile was similar between seropositive and seronegative subjects with heart failure. We found that the different clinical stages of chronic Chagas disease displayed distinct monocyte profiles, which are susceptible to being restored by modulating the parasite load with anti-parasite drug therapy. T. cruzi-infected subjects with severe cardiac disease displayed a profile of monocytes subsets suggestive of a more pronounced inflammatory environment compared with subjects suffering from heart failure not related to T. cruzi infection, supporting that parasite persistence might be a detrimental factor in the evolution of the cardiac disease induced by T. cruzi.

Perturbed T cell IL-7 receptor signaling in chronic Chagas disease

We have previously demonstrated that immune responses in subjects with chronic Trypanosoma cruzi infection display features common to other persistent infections with signs of T cell exhaustion. Alterations in cytokine receptor signal transduction have emerged as one of the cell-intrinsic mechanisms of T cell exhaustion. In this study, we performed an analysis of the expression of IL-7R components (CD127 and CD132) on CD4(+) and CD8(+) T cells and evaluated IL-7-dependent signaling events in patients at different clinical stages of chronic chagasic heart disease. Subjects with no signs of cardiac disease showed a decrease in CD127(+)CD132(+) cells and a reciprocal gain of CD127(-)CD132(+) in CD8(+) and CD4(+) T cells compared with either patients exhibiting heart enlargement or uninfected controls. T. cruzi infection, in vitro, was able to stimulate the downregulation of CD127 and the upregulation of CD132 on T cells. IL-7-induced phosphorylation of STAT5 as well as Bcl-2 and CD25 expression were lower in T. cruzi-infected subjects compared with uninfected controls. The serum levels of IL-7 were also increased in chronic chagasic patients. The present study highlights perturbed IL-7/IL-7R T cell signaling through STAT5 as a potential mechanism of T cell exhaustion in chronic T. cruzi infection.

Sequential combined treatment with allopurinol and benznidazole in the chronic phase of Trypanosoma cruzi infection: a pilot study

OBJECTIVES

Even though the use of combined drugs has been proved to be effective in other chronic infections, assessment of combined treatment of antiparasitic drugs in human Chagas' disease has not been performed. Herein, a pilot study was conducted to evaluate the tolerance and side effects of a sequential combined treatment of two antiparasitic drugs, allopurinol and benznidazole, in the chronic phase of Trypanosoma cruzi infection.

PATIENTS AND METHODS

Changes in total and T. cruzi-specific T and B cells were monitored during a median follow-up of 36 months. Allopurinol was administered for 3 months (600 mg/day) followed by 30 days of benznidazole (5 mg/kg/day) in 11 T. cruzi-infected subjects.

RESULTS

The combined sequential treatment of allopurinol and benznidazole was well tolerated. The levels of T. cruzi-specific antibodies significantly decreased after sequential combined treatment, as determined by conventional serology and by a multiplex assay using recombinant proteins. The frequency of T. cruzi-specific interferon-γ-producing T cells significantly increased after allopurinol treatment and decreased to background levels following benznidazole administration in a substantial proportion of subjects evaluated. The levels of total naive (CD45RA + CCR7 + CD62L+) CD4 + and CD8 + T cells were restored after allopurinol administration and maintained after completion of the combined drug protocol, along with a decrease in T cell activation in total peripheral CD4 + and CD8 + T cells.

CONCLUSIONS

This pilot study shows that the combination of allopurinol and benznidazole induces significant modifications in T and B cell responses indicative of a reduction in parasite burden, and sustains the feasibility of administration of two antiparasitic drugs in the chronic phase of Chagas' disease.

Seronegative conversion after incomplete benznidazole treatment in chronic Chagas disease

In 12-18% of adult patients, treatment with benznidazole for chronic Chagas disease has to be discontinued because of side-effects. We identified and analysed a cohort of 81 adult patients with three positive tests for Trypanosoma cruzi infection and serological monitoring following incomplete treatment with benznidazole for a median of 10 days. Twenty percent of these patients (16/81) met the criteria of cure, showing that the optimal schedule of benznidazole administration remains to be determined.

Impact of aetiological treatment on conventional and multiplex serology in chronic Chagas disease

BACKGROUND

The main criterion for treatment effectiveness in Chagas Disease has been the seronegative conversion, achieved many years post-treatment. One of the main limitations in evaluating treatment for chronic Chagas disease is the lack of reliable tests to ensure parasite clearance and to examine the effects of treatment. However, declines in conventional serological titers and a new multiplex assay can be useful tools to monitor early the treatment impact.

METHODOLOGY/PRINCIPAL FINDINGS

Changes in antibody levels, including seronegative conversion as well as declines in titers, were serially measured in 53 benznidazole-treated and 89 untreated chronic patients in Buenos Aires, Argentina with a median follow-up of 36 months. Decrease of titers (34/53 [64%] treated vs. 19/89 [21%] untreated, p<0.001) and seronegative conversion (21/53, [40%] treated vs. 6/89, [7%] untreated, p<0.001) in at least one conventional serological test were significantly higher in the benznidazole-treated group compare with the untreated group. When not only complete seronegative conversion but also seronegative conversion on 2 tests and the decreases of titers on 2 or 3 tests were considered, the impact of treatment on conventional serology increased from 21% (11/53 subjects) to 45% (24/53 subjects). A strong concordance was found between the combination of conventional serologic tests and multiplex assay (kappa index 0.60) to detect a decrease in antibody levels pos-treatment.

CONCLUSIONS/SIGNIFICANCE

Treatment with benznidazole in subjects with chronic Chagas disease has a major impact on the serology specific for T. cruzi infection in a shorter follow-up period than previously considered, reflected either by a complete or partial seronegative conversion or by a significant decrease in the levels of T. cruzi antibodies, consistent with a possible elimination or reduction of parasite load.

Changes in Trypanosoma cruzi-specific immune responses after treatment: surrogate markers of treatment efficacy

BACKGROUND

As many as 20 million people are living with Trypanosoma cruzi infection in Latin American, yet few receive any treatment. The major limitation in developing and evaluating potential new drugs for their efficacy is the lack of reliable tests to assess parasite burden and elimination.

METHODS

Adults volunteers with chronic T. cruzi infection were evaluated clinically and stratified according to the Kuschnir classification. Individuals with group 0 and group 1 clinical status were treated with benznidazole (5 mg/kg per day for 30 days). The changes in T. cruzi-specific T cell and antibody responses, as well as in clinical status, were measured periodically over the 3-5-year follow-up period and were compared with pretreatment conditions and with values in an untreated control group.

RESULTS

The frequency of peripheral interferon (IFN)-gamma-producing T cells specific for T. cruzi declined as early as 12 months after benznidazole treatment and subsequently became undetectable in a substantial proportion of treated subjects. In addition, decreases in antibody responses to a pool of recombinant T. cruzi proteins also decreased in many of these same subjects. The shift to negative IFN-gamma T cell responses was highly associated with an early increase in IFN-gamma-producing T cells with phenotypic features of effector/effector memory cells in a subset of subjects. Benznidazole treatment also resulted in an increase in naive and early differentiated memory-like CD8(+) T cells in a majority of subjects.

CONCLUSIONS

Benznidazole treatment during chronic Chagas disease has a substantial impact on parasite-specific immune response that is likely indicative of treatment efficacy and cure.

[Predictors of heart failure in chronic chagasic cardiomyopathy with asymptomatic left ventricular dysfunction]

INTRODUCTION AND OBJECTIVES

The development of asymptomatic left ventricular dysfunction signifies a worsening of chronic chagasic cardiomyopathy. Our objective was to identify factors that predict the development of heart failure and all-cause mortality.

METHODS

The study included 95 patients with an echocardiographic diagnosis of asymptomatic left ventricular dysfunction. The patients' clinical, electrocardiographic and echocardiographic characteristics were recorded. Factors associated with the development of heart failure were evaluated by Cox regression modeling. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated. Receiver operating characteristic (ROC) curves were used to evaluate the sensitivity and specificity of continuous variables identified as significant in the regression analysis.

RESULTS

Patients (mean age, 55 [11] years) were followed up for a median of 63 months (interquartile range, 32-110 months). Univariate analysis showed that there were significant differences in mild and severe systolic dysfunction, age on admission, and E-point-to-septal separation, while the only significant predictors of heart failure found on Cox regression analysis were severe systolic dysfunction (HR=3.53; 95% CI, 1.21-10.30; P=.021) and E-point-to-septal separation (HR=1.12; 95% CI, 1.02-1.23; P=.014). The mortality rate was 3% (3/95) in patients who continued to have asymptomatic left ventricular dysfunction and 37% (10/27) in those who developed heart failure.

CONCLUSIONS

The E-point-to-septal separation and the presence of severe systolic dysfunction can serve as predictors of heart failure in patients with chronic chagasic cardiomyopathy and asymptomatic left ventricular dysfunction.

Long-term cardiac outcomes of treating chronic Chagas disease with benznidazole versus no treatment: a nonrandomized trial

BACKGROUND

Benznidazole is effective for treating acute-stage Chagas disease, but its effectiveness for treating indeterminate and chronic stages remains uncertain.

OBJECTIVE

To compare long-term outcomes of patients with nonacute Chagas disease treated with benznidazole versus outcomes of those who did not receive treatment.

DESIGN

Clinical trial with unblinded, nonrandom assignment of patients to intervention or control groups.

SETTING

Chagas disease center in Buenos Aires, Argentina.

PATIENTS

566 patients 30 to 50 years of age with 3 positive results on serologic tests and without heart failure.

MEASUREMENTS

The primary outcome was disease progression, defined as a change to a more advanced Kuschnir group or death. Secondary outcomes included new abnormalities on electrocardiography and serologic reactivity.

INTERVENTION

Oral benznidazole, 5 mg/kg of body weight per day for 30 days (283 patients), or no treatment (283 patients).

RESULTS

Fewer treated patients had progression of disease (12 of 283 [4%] vs. 40 of 283 [14%]; adjusted hazard ratio, 0.24 [95% CI, 0.10 to 0.59]; P = 0.002) or developed abnormalities on electrocardiography (15 of 283 [5%] vs. 45 of 283 [16%]; adjusted hazard ratio, 0.27 [CI, 0.13 to 0.57]; P = 0.001) compared with untreated patients. Left ventricular ejection fraction (hazard ratio, 0.97 [CI, 0.94 to 0.99]; P < 0.002) and left ventricular diastolic diameter (hazard ratio, 2.45 [CI, 1.53 to 3.95]; P < 0.001) were also associated with disease progression. Conversion to negative results on serologic testing was more frequent in treated patients than in untreated patients (32 of 218 [15%] vs. 12 of 212 [6%]; adjusted hazard ratio, 2.1 [CI, 1.06 to 4.06]; P = 0.034).

LIMITATIONS

Nonrandom, unblinded treatment assignment was used, and follow-up data were missing for 20% of patients. Loss to follow-up was more common among patients who were less sick. Two uncontrolled interim analyses were conducted.

CONCLUSIONS

Compared with no treatment, benznidazole treatment was associated with reduced progression of Chagas disease and increased negative seroconversion for patients presenting with nonacute disease and no heart failure. These observations indicate that a randomized, controlled trial should now be conducted.

[Clinical predictors of chronic chagasic myocarditis progression]

INTRODUCTION AND OBJECTIVES

Previous prognostic studies of Chagas' disease have focused on mortality associated with end-stage cardiopathy (i.e., heart failure). Our aim was to identify indicators of progression in early-stage Chagas' heart disease.

MATERIAL AND METHOD

The study included 856 patients with 3 positive anti-Trypanosoma cruzi test results. Those with heart failure were excluded. Patients were divided into 3 clinical groups: those without heart disease (Group I); those with heart disease but without left ventricular enlargement (Group II); and those with left ventricular enlargement but without heart failure (Group III). The endpoint was progression to a more severe clinical stage or death due to cardiovascular disease. A Cox regression model was used to derive a clinical risk score from clinical, electrocardiographic and echocardiographic variables.

RESULTS

At study entry, the patients' mean age was 43.7 years. They were followed up for a mean of 8 years. The following were predictors of heart disease progression: age at entry (HR=1.05; 95% CI, 1.02-1.07; P<.001), left ventricular systolic diameter (HR=1.06; 95% CI, 1.04-1.09; P<.001), intraventricular conduction abnormalities (HR=1.85; 95% CI, 1.02-3.36; P=.04), and sustained ventricular tachycardia (HR=3.97; 95% CI, 1.65-9.58; P=.002). Treatment with benznidazole reduced the risk of progression (HR=0.40; 95% CI, 0.23-0.72; P=.002). The devised clinical risk score was effective in stratifying the likelihood of cardiopathy progression.

CONCLUSIONS

Specific clinical indicators and a derived clinical risk score can be used to predict the progression of chronic chagasic myocarditis in patients without heart failure.

Value of echocardiography for diagnosis and prognosis of chronic Chagas disease cardiomyopathy without heart failure

OBJECTIVES

To establish the usefulness of echocardiography for the clinical classification of patients with Chagas disease and to determine the predictors of mortality and clinical events.

METHODS

849 patients with chronic Chagas disease with a mean follow up of 9.9 years were studied. On admission, ECG, chest radiograph, and two dimensional echocardiogram were obtained from all patients. Clinical events were defined as new ECG abnormalities, change in clinical status resulting in transfer to another group, and death. Morphologically characterised segmental lesions were also seen in 12 patients on a second harmonic echocardiogram with intravenous contrast agent. Univariate and multivariate analysis for clinical events and mortality were performed.

SETTING

Community of San Martín, Buenos Aires, Argentina.

RESULTS

Change in clinical group (68 of 833 survivors v 15 of 16 who died, p < 0.001), left ventricular systolic dimension (mean (SD) 3.06 (0.72) cm v 4.71 (0.90) cm, p < 0.0001), and ejection fraction (mean (SD) 0.67 (0.11)% v 0.42 (0.17)%, p < 0.0001) were found to be the only predictors of mortality. ECG abnormalities related to the disease (in 220 of 699 patients with no clinical event v 98 of 150 patients with a clinical event, p < 0.0001), left ventricular diastolic dimension (mean (SD) 4.88 (0.54) cm v 5.44 (0.83) cm, p < 0.0001), left ventricular systolic dimension (mean (SD) 2.98 (0.62) cm v 3.64 (1.03) cm, p < 0.0001), and ejection fraction (mean (SD) 0.68 (0.10)% v 0.60 (0.16)%, p < 0.0001) were predictors of clinical events. Segmental lesions were observed in 211 of 849 patients (25%). Segmental lesions were seen in 66 (13%) and systolic dysfunction was seen in four of 505 (0.8%) patients with normal ECG. Significant differences were found between the groups of patients (group 0: reactive serology and normal ECG and chest radiography without cardiac enlargement and no signs of heart failure; group 1: reactive serology and abnormal ECG and chest radiography without cardiac enlargement; group 2: reactive serology and abnormal ECG and chest radiography with cardiac enlargement and no signs of heart failure).

CONCLUSION

Echocardiography was useful both to characterise and to determine the prognosis of patients with chronic Chagas disease without heart failure.

[The characteristics and properties of calcium phosphates in biomaterial formulations used in dentistry. 1]

In this work we present the features and the properties of natural and synthetic apatites, which we use in an experimental study of various commercial products composed by calcium phosphate. After having considered the general concepts of biomaterials and biocompatibility, we describe non biological tests used for the characterization of these products. Biomaterials used in this study are: reabsorbable Dac Blu, non reabsorbable Dac Blu, non reabsorbable atomized Dac Blu, non reabsorbable thin Dac Blu, reabsorbable Biocoral 450, Calcitite 2040-12, Orthogel, Apagen, BTF 65, Calcitite 4060-2 Osprogel, Bio-oss, Biostite, Osprovit, Merck Hydroxiapatite. Tests used are: X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and thermodifferential analysis (TG, DTG, DTA), scanner-ing electron microscopy (SEM) morphological analysis. Last but not least, we underline the particular features of these tests whose interpretation allows a more precise definition of the bioactivity of a biocompatible material.

[The X-ray fluorescence (XRF) spectrometry of biomaterials used in dentistry. 2]

In this work we analyze the following biomaterial: biomaterials used in this study are: reabsorbable Dac Blu, non reabsorbable Dac Blu, non reabsorbable atomized Dac Blu, non reabsorbable thin Dac Blu, reabsorbable Biocoral 450, Calcitite 2040-12, Orthogel, Apagen, BTF 65, Calcitite 4060-2, Osprogel, Bio-Oss, Biostite, Osprovit, Merck Hydroxiapatite. The quantitative XRF analysis was performed by a Philips PW 1480 with Rh tube. This research, besides underlining the possibility of applying the XRF method to the analysis of biomaterials. This study, shows the facility and the rapidity in the preparation of samples and standards in the form of tablets to undergo the analysis: furthermore the study shows the possibility of verify the analysis on the same sample in the future, because the tablet if well conserved, does not deteriorate. We can also verify a good analytic accuracy both for the principal elements (Ca, P) and for trace elements. The analyses show a moderate variability in the Ca/P ratio in the hydroxylapatites, and a greater variability in the secondary and trace elements.

[The specific characteristics determined by nonbiological tests of mineral-based biomaterials used in dentistry. 7]

In this work we relate about the results coming from crystallographic, physical and mineral tests taken on following biomaterials used in odontostomatology: reabsorbable Dac Blu, non reabsorbable Dac Blu, not reabsorbable atomized Dac Blu, not reabsorbable thin Dac Blu, reabsorbable Biocoral 450, Calcitite 2040-12, Orthogel, Apagen, BTF 65, Calcitite 4060-2, Osprogel, Bio-Oss, Biostite, Osprovit, Merck Hydroxiapatite. The data were obtained using the following tests: XRF, XRD, FTIR, TG, DTG, DTA, SEM. The results, although taken on few samples, showed that these biomaterials present a variability in some features, which can define the structural functionality.

A new material with theoretical osteoinductive properties: experimental evaluation

An intensive research for bone substitutes has been in progress for several decades in order to find a new ideal material for bone replacement. In the present study the Authors report some data on a new developed material in comparison with synthetic hydroxyapatite. The new material was characterised by means of a crystallographic spectroscopic and chemical study. An in vitro test was also performed using murine fibroblasts. The results of this preliminary study showed that the sintered material has an and beta-tricalcium-phosphate (TCP) lattice depending on thermal treatment in accordance with literature data. Moreover, it showed a high level of biocompatibility. Though it is still in an investigation stage, perhaps this biomaterial is a highly reactive and unstable compound that could interact with CO2 and H2O.

Scanning electron microscopy, chemical and histologic analysis in human periarthritic shoulder biopsy

In the present study biopsies were analyzed, taken from the left shoulder of a patient who, according to the radiological diagnosis, was suffering from calcific periarthritis. In both optical and electronic microscopy the mineralogical observations showed crystalline aggregations, while the chemical analysis, carried out with an Edax EDS spectrophotometer, confirmed the presence of Ca and P in them, in the ratio typical of biological apatites. The histological observations clearly indicate a change in the metabolism of the tissues present. In the samples observed the damage to the muscular tissues is easily seen while the connective tissue, though apparently less compromised, shows the presence of numerous calcifications whose damage cannot be revealed solely through histologic observations. The authors, linking the structural histologic alterations observed to the presence of hydroxyapatite granules as well as to the patient's painful symptoms, believe all these observations are the result of a chronic process.

Osteoporosis by ovariectomy: calcitonin effect in an experimental model on the rat

The authors evaluate the efficacy of the aminosuberic derivative of eel calcitonin (eCT) in preventing post-ovariectomy osteoporosis in adult rats. The drug is administered in a dose of 0.5 U.I./day for four months starting from the moment of the ovariectomy. The results show that the treatment is efficacious in preventing bone mass loss due to ovariectomy and that the action of the drug does not bring about alterations in the normal crystalline structure of the bone.

Thermodynamical aspects of the polymerization reaction of PMMA cement mixed with phosphatic mineral phases

The main problem related to the use of polymeric cement in orthopaedics is the high temperature reached during the polymerization, causing necrosis. This paper reports a thermodynamical study of the polymerization reaction of an acrylic cement mixed with powdered phosphatic phases. In particular, mixing of alpha-tricalciumphosphate, beta-tricalciumphosphate and hydroxyapatite was proposed. Important preliminary results indicated that amounts of about 66% by weight of alpha-tricalciumphosphate reduced the polymerization temperature to about 58 degrees C in respect to 100 degrees C of pure acrylic cement. In addition, a special chamber was designed and realized to monitor the temperature variations involved during the polymerization reaction of the different mixtures.

Chemistry and structure of a new canal sealer showing a dynamical behaviour

The complete apical seal without percolation and transit of bacteria and their products along the wall of the endodontic canal is the fundamental condition to obtain a lasting result of a correct endodontic therapy. The aim of this study was to characterize a new formulation cement (PROENDO, VEBAS, Italy) with characteristics totally different from the conventional ones. Finally, we can assert that an alloplastic material like PROENDO, which is the subject of this study, bio-compatible, osteo-inductive, non-toxic, with adhesive capacities, is able to quicken the phenomena of restoration and recovery after an endodontic operation.

Morphological and structural characteristics of the myopathic bone

The aim of the present paper was to study the myopathic bone both from the morphological and structural viewpoints. To this end, samples from 8 patients affected by different neuromuscular diseases (DMD, SMA and CMD) have been examined. Thus, by SEM analysis a quantitative reduction of the trabeculae and an increase in porosity of the myopathic bone were found and also, by diffractometric analysis, the presence of pathologic crystalline phases (beta-TCP and beta-TCP-Mg).

Influence of calcitonin treatment on the bone structure and mineral content in osteoarthritis

8 femoral heads removed in 4 patients operated on by bilateral total hip replacement for osteoarthritis were evaluated. 3 patients were treated with Calcitonin between the first and the second operation. X-ray powder diffractometry analysis showed an improvement of bone crystallinity in the Calcitonin treated patients.

SEM and chemical micro-analysis in a failed total knee prosthesis

Authors performed SEM and EDS analyses in a cemented removed knee prosthesis demonstrating the average values of mineral elements in the bone surrounding the prosthesis. The composition of the metallic prosthesis surface in different microareas was also studied.

Calcium oxalate smear layer: mineralogical and crystallographic study

Different methods to reduce dentine hypersensitivity have been tested by means of oxalate treatments. Natural material (20 teeth) and commercial oxalates have been employed. As a result the dentinal tubules are filled by small crystals preventing dental disease. Permeability measurements have been performed in order to quantify results. The composition of the synthetic smear layer produced after oxalate treatment have been investigated by powder diffraction method suggesting calcium oxalate formation.

Microleakage in composite resin restorations

The aim of the present study was to evaluate the marginal microleakage of the newest generation of composite resin restorative materials. Class V restorations were prepared in human extracted teeth. Different combinations of restorative materials were used. All the materials tested showed marginal microleakage along the dentinal walls, suggesting that the adhesion value is not sufficient to counteract the composite shrinkage and to reduce the marginal space.

Influence of the fluoride ion in the stability of bone hydroxyapatite achieved in patients after the fluo-calcic therapy

It has been proposed that fluoride ion might actively enter into the basic structural framework of the bone, within its main constituent, the hydroxyapatite (HA), by substituting systematically the OH- ion in the crystal chemical formula Ca5[(PO4)3OH]. Accurate compositional studies have become necessary in order to explain an eventual stabilizing effect. Loss in weight (TG) and chemical reaction (DTG) while varying the temperature have been carried out for the first time on specimens under normal conditions and after fluo-calcic treatment, in parallel with accurate chemical compositional determinations by atomic absorption analysis. Our investigation shows that the new structure present after treatment is mechanically stable and proves more resistant to osteolytic processes.

Dental composite resin porosity and effect on water absorption

The aims of this study were: 1) to characterize the solubility and water absorption of different composite resins used as dental restorative materials; 2) to analyse their surface morphology using S.E.M. The resins tested were a mixture of glycidyl methacrylate (Bis-GMA) and TEGMA filled with silane-coated particles of inorganic fillers, and Bis-GMA and urethane resin. Cylindrical samples of composite resin were polymerized and stored in distilled water and weighed after different times. SEM analysis demonstrated voids and porous in several samples. The present study shows that dental restorative composite loose a small percentage of their components during storage time and that the type of resin, the nature of fillers and the methods of polymerization greatly influence water uptake and solubility of dental composite resin materials. These findings could explain the loss of anatomic form and the occlusal degradation of dental composites in "in vivo" conditions.

Determination of the mineral elements in the pollen of some Gymnospermae

In this work the principal elements (K, Ca, Fe, Mg, Cu, Zn, Mn, Na) constituting the mineral component of the pollen in some Gymnospermae, have been determined. This type of investigation has few matches in literature despite the importance some mineral elements have in germinating the pollen granule. The pollen samples, appropriately treated, were analysed in atomic absorption spectrophotometry and biometrically characterized under the optical microscope. Examination of the analytical data allows verification of the great influence deriving from soil characteristics and, within the families, a specific role of the type. The morphobiometric parameters show that a link exists between small and medium granules and with thin walls and minimum concentration values of Na, Fe, Cu, Zn and Mn.

Evaluation of the relative rates of bone mineral content loss in postmenopause due to both estrogen deficiency and ageing

To evaluate the relative rates of bone mineral content loss in postmenopause due to both estrogen deficiency and ageing, three groups of women were studied by computerized bone densitometry at the radius mid-point and at the distal point, modified according to the Abwrey technique. All women were in apparent good health and never had estrogen therapy. In the first group there were 64 women aged between 30 and 50 who were ovariectomized between 25 and 35 years of age. The second group was made up of 309 women between 50 and 55 years. In the third group there were 136 women aged 30-50 with normal ovaric function. The ordinary functions of linear polynomial regression were used to describe the variations in density with age. The percentage of postmenopausal bone loss was determined by calculating the BMC value at the start of the menopause and again twenty years later, according to the linear regression equation of postmenopausal period of each group of women in the study. The women who had natural menopause showed an average bone loss per year of 1.63% at the mid radius and 1.0% at the distal point. The ovariectomized women had an average loss of 0.85% at the mid point and 0.66% at the distal point. No significant decrease of bone mass was found before menopause. From a comparison between the two groups of women with analogous periods of menopause, it comes out that, during the first 20 years of natural menopause, estrogen deficiency is responsible for 52.5%-66.4% of the bone mineral loss, the remaining amount being attributable to other causes, connected with ageing. Estrogen deficiency is therefore, the principal factor causing bone mineral loss in natural menopause.

Bone mineral alterations and Mg content in aging

The authors propose to determine whether the quantity of bone mass reduction linked to aging is accompanied by qualitative modifications of the mineral structure. To this end, 18 samples of cancellous bone from the femoral heads of two groups of patients (Groups A & B), were examined. Group A was made up of 8 old osteopenic patients suffering from fracture of the femur neck (age 62-84). Group B consisted of 10 young non-osteopenic subjects (age 34-53). Through chemical analysis a statistically significant percentage increase in Mg++ was noted in Group A and, by X-Ray diffraction, significant presence of beta-TCP. Mineral structure alterations occur in the process of aging of the skeletal tissue.

Densitometric analysis in in vivo evaluation of synthetic salmon calcitonin activity

In women suffering from post-menopausal osteoporosis, we evaluated the effectiveness of two cyclic treatments with synthetic salmon calcitonin over a whole year, using an average daily dose of 16 and 32 IU, respectively. This treatment was compared with treatment with oral calcium carbonate. The results, evaluated by peripheral densitometry of the radius, showed a 3.2% loss of bone mineral content (BMC) in the women treated only with calcium carbonate, a loss of 1% in those treated with an average dose of 16 IU/day of calcitonin and an increase of 4% in the women treated with an average dose of 32 IU/day (an increase just above the statistically significant limit using the paired t-test). An average dose of 32 IU/day probably represents the minimum effective dose of calcitonin required to produce a significant increase in bone mineral mass, when used according to a sequential scheme.

Synthesis and antimycotic activity of some benzyloxyimino compounds

Some benzyloxyimio compounds, related to oxiconazole and having a 1H-indole or 1H-benzimidazole moiety, have been synthesized and tested in vitro for their antimycotic activity against Candida tropicalis and C. albicans. The most active was showed to be 0-(2,4-dichlorobenzyl)-1-benzyl-5-nitro-1H-benzimidazole-2-carboxaldehyd e oxime (MIC: 25 micrograms/ml against both microorganisms). A structural feature important for the biological activity of the series appears to be presence of a benzimidazole nucleus substituted by an electron withdrawing group.