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BACKGROUND Chagas disease is one of the most common diseases in Latin-America, and cardiac involvement is a significant cause of death. Assessment of myocardial strain may detect early myocardial damage. OBJECTIVES To determine differences in longitudinal strain using speckle tracking to assess regional and global left ventricular function in patients with the indeterminate form of Chagas disease, in comparison with a control group. METHODS This is a retrospective matched case-control study, conducted in a single center. We evaluated 45 adult patients with Chagas disease, diagnosed with 2 serological methods, without evidence of cardiac involvement, who were compared with 45 healthy control subjects, who were sex- and age-matched. All patients underwent Doppler echocardiography and longitudinal strain with speckle tracking. RESULTS Median age was 59 years, and 60% were female. Echocardiographic parameters were similar in patients with Chagas and control subjects. In patients with Chagas, global strain differed significantly from that of control subjects (-17 vs -20.3, P < .001). Segmental strain showed 7 abnormal segments in patients with Chagas (P < .05). CONCLUSIONS In patients with the indeterminate form of Chagas disease, global and segmental longitudinal peak systolic strain is reduced compared with healthy subjects, thus suggesting that it could be a sensitive technique to detect early myocardial damage. These findings could provide useful information regarding the pathophysiology of cardiac involvement and understand whether they might have prognostic usefulness or help develop strategies to modify the course and prognosis of patients with Chagas disease. A longitudinal prospective study would be necessary to validate our findings.

The character of inheritance of the determinate stem growth type in a garden pea form having four productive nodes (cv. Pervenets with a dwarf stem) has been first studied. The analysis of first-generation hybrids obtained from crosses between indeterminate forms and determinate samples (DTR-2 and DTR-4) showed that the phenotype of all plants was characterized by a usual stem growth type and formation of buds in the stipule axiles. In the case of DTR crosses between themselves, all plants corresponded to the DTR-2 phenotype. In the case of the cross combination (indeterminate form × DTR-2), segregation at a 3 : 1 ratio was observed in the second generation. In the case of the (indeterminate form × DTR-4) variant, phenotypes of resulting plants were segregated into four classes indicating the presence of two genes. For the (DTR-2 × DTR-4) cross, a 3 : 1 segregation was observed in relation to the early bud production. The inheritance of the “number of productive nodes” trait in the cv. Pervenets is determined by two genes, one of which is not related to the determination. This fact was confirmed by the test crossing with the further evaluation of the deviation of the actual segregation from the expected one using the χ2 (chi-square) method. According to the obtained data, the crossing [DTR-2 × (Voronezhsky zeleniy × Ranniy 28-11-early budding)] resulted in a new variety characterized by a limited stem growth type and four fertile nodes that is suitable for mechanical harvesting.

For the first time the character of the inheritance of the determinant form with four productive nodes (variety Pervenets with a dwarf stem). The analysis of first-generation hybrids obtained from crosses of indeterminate forms with determinant samples (DTR-2 and DTR-4) showed that all the plants had a phenotype with the usual type of stem growth and the formation of buds in the axiles of stipules. When the DTR was crossed all the plants corresponded to the phenotype of DTR-2. In the second generation in the combination (indeterminant x DTR-2) a splitting was foynd in a ratio of 3:1; in F2 (the indeterminant x DTR-4) in the phenotype the plants were divided into four phenotypic classes, that indicates the presence of two genes; in (DTR-2 x DTR-4) the discrepancy was due to the early emission of buds and corresponded to 3:1. The inheritance of the feature number of productive nodes (CNC) in the Pervenets variety is due to two genes, one of which is not related to determination. This is confirmed by the analyzing crossing and calculation of the deviation of the correspondence of the actual splitting according to theoretically expected, using the 2 (hi-square) method. According to the obtained data, crossing was done [DTR-2 x VZR-28-11 (early budding)] resulting in a new variety with a limited type of stem growth, number of fertile nodes 4, suitable for mechanized harvesting.

Malaltia de Chagas; Trypanosoma cruzi; Variabilitat genètica Chagas disease; Trypanosoma cruzi; Genetic variability Enfermedad de Chagas; Trypanosoma cruzi; Variabilidad genética Background: Trypanosoma cruzi has a high rate of biological and genetic variability, and its population structure is divided into seven distinct genetic groups (TcI-TcVI and Tcbat). Due to immigration, Chagas disease (ChD), caused by T. cruzi, has become a serious global health problem including in Europe. Therefore, the aim of this study was to evaluate the existence of genetic variability within discrete typing unit (DTU) TcV of T. cruzi in Bolivian patients with chronic ChD residing in Barcelona, Spain. Methods: The DNA was extracted from the peripheral blood of 27 patients infected with T. cruzi DTU TcV and the fragments of the genetic material were amplificated through the low stringency single primer-polymerase chain reaction (LSSP-PCR). The data generated after amplification were submitted to bioinformatics analysis. Results: Of the 27 patients evaluated in the study, 8/27 (29.6%) were male and 19/27 (70.4%) female, 17/27 (62.9%) were previously classified with the indeterminate clinical form of Chagas disease and 10/27 (37.1%) with Chagas cardiomyopathy. The LSSP-PCR detected 432 band fragments from 80 to 1,500 bp. The unweighted pair-group method analysis and principal coordinated analysis data demonstrated the existence of three distinct genetic groups with moderate-high rates of intraspecific genetic variability/diversity that had shared parasite's alleles in patients with the indeterminate and cardiomyopathy forms of ChD. Conclusions: This study demonstrated the existence of a moderate to high rate of intra-DTU TcV variability in T. cruzi. Certain alleles of the parasite were associated with the absence of clinical manifestations in patients harboring the indeterminate form of ChD. These results support the need to search for increasingly specific targets in the genome of T. cruzi to be correlated with its main biological properties and clinical features in patients with chronic ChD. This work was supported by São Paulo Research Foundation (FAPESP)- fapesp.br/en (Grant No. 2018/22093-4), São Paulo Research Foundation (FAPESP)- fapesp.br/en (Grant No. 2019/11943-0), São Paulo Research Foundation (FAPESP)- fapesp.br/en (Grant No. 2016/25403-9), and Universitat Autònoma de Barcelona, Vall d'Hebron University Hospital, PROSICS Barcelona, Spain.

Objective Investigate whether heart rate variability (HRV) indices can be used to predict morpho-functional parameters obtained from the echocardiogram in a population of patients with Chagas disease (CD). Methods Sixty-three patients with CD and a recent echocardiogram had their ECG and respiratory signals recorded for 15 min. The cardiac interval series were generated from the ECG and 27 HRV indices, plus the respiratory frequency, were calculated. The correlation between HRV and echocardiographic variables was estimated. The HRV indices were also utilized as inputs in four machine learning schemes to create predictive models for numeric and categorical echocardiographic parameters. Attribute selection schemes were also performed to identify the subset of HRV indices that best represent each parameter for each machine learning algorithm. Results Only three echocardiographic parameters had no HRV index significantly correlated to them. The most frequently selected HRV index in the attribute selection process was the fractal short-term scaling exponent. The regression models (numeric parameters) reached reasonable performance (R > 0.5) for all except two parameters, while the classification models (categorical variables) achieved better performance, with precision and recall values higher than 0.74. Conclusion HRV indices, both isolated and combined, are associated with cardiac morpho-functional properties in patients with CD, and may be used to predict echocardiographic parameters. Significance The possibility of modeling the cardiac morpho-functional parameters in patients with CD using HRV indices opens the possibility to use HRV for risk assessment in patients with CD, especially those harboring the indeterminate form of the disease.

Chagas disease (CD) remains a serious endemic disease in Latin America and a major public health problem. Because of globalization, the disease has spread to non-endemic areas in the northern hemisphere. In the chronic phase of the disease, most patients present with the indeterminate form (IF), characterized by positive serology for Trypanosoma cruzi, absence of clinical findings, and normal findings in electrocardiogram (ECG). IF was not recognized as a clinical entity until decades after the discovery of the disease, and only in the 1940-50s, it was categorized as a form of CD, and its conceptual definition was ratified in the 1980s. Children, adolescents, and young adults with the IF benefit from etiological treatment and tend to have less progression to heart disease in the long term than the untreated ones. IF patients have an essentially benign clinical condition, and their prognosis can be compared to that of healthy individuals with normal ECG findings. Currently, because of aging, patients with the IF have comorbidities that require attention in health services.

Background Chagas disease (CD) remains an important endemic disease in Latin America. However, CD became globalized in recent decades. The majority of the chronically infected individuals did not receive etiologic treatment for several reasons, among them the most conspicuous is the lack of access to diagnosis. The impact of trypanocidal treatment on CD chronic phase, without cardiac involvement (indeterminate form ICF), is yet to be determined. We aimed to evaluate the effect of trypanocidal treatment with benznidazole (BZN) on the rate of progression to Chagas heart disease in patients with ICF. Methods This is a retrospective cohort observational study including patients with ICF treated with BZN and compared to a group of non-treated patients matched for age, sex, region of origin, and the year of cohort entry. We reviewed the medical charts of all patients followed from May 1987 to June 2020 at the outpatient center of the Evandro Chagas National Institute of Infectious Diseases (INI) of the Oswaldo Cruz Foundation (Fiocruz), Rio de Janeiro, Brazil. Patients' follow-up included at least one annual medical visit and one annual electrocardiogram (ECG). Echocardiographic exams were performed at baseline and during the follow-up. Disease progression from ICF to cardiac form was defined by changes in baseline ECG. Cumulative incidence and the incidence rate were described in the incidence analysis. Cox proportional hazards models were used to estimate hazard ratios and 95% confidence intervals for the association between BZN and CD progression, cardiovascular events or death. Findings One hundred and fourteen treated patients met the study inclusion criteria. A comparison group of 114 non-treated patients matched for age, sex, region of origin, and the year of cohort entry was also included, totalizing 228 patients. Most patients included in the study were male (70.2%), and their mean age was 31.3 (+7.4) years. Over a median follow-up of 15.1 years (ranging from 1.0 to 32.4), the cumulative CD progression incidence in treated patients was 7.9% vs. 21.1% in the non-treated group (p = 0.04) and the CD progression rate was 0.49 per 1.000 patients/year in treated patients vs. 1.10 per 1.000 patients/year for non-treated patients (p = 0.02). BZN treatment was associated with a decreased risk of CD progression in both unadjusted (HR 0.46; 95%CI 0.21 to 0.98) and adjusted (HR 0.43; 95%CI 0.19 to 0.96) models and with a decreased risk of occurrence of the composite of cardiovascular events only in the adjusted (HR 0.15; 95%CI 0.03 to 0.80) model. No association was observed between BZN treatment and mortality. Interpretation In a long-term follow-up, BZN treatment was associated with a decreased incidence of CD progression from ICF to the cardiac form and also with a decreased risk of cardiovascular events. Therefore, our results indicate that BZN treatment for CD patients with ICF should be implemented into clinical practice.

Chagas disease (CD) will account for 200,000 cardiovascular deaths worldwide over the next 5 years. Early detection of chronic Chagas cardiomyopathy (CCC) is a challenge. We aimed to test if speckle-tracking echocardiography (STE) can detect incipient myocardial damage in CD. METHODS: Among 325 individuals with positive serological tests, 25 (age 55±12yrs) were selected to compose the group with indeterminate form of Chagas disease (IFCD), based on stringent criteria of being asymptomatic and with normal EKG/X-ray studies. This group was compared with a group of 20 patients with CCC (55±11yrs) and a group of 20 non-infected matched control (NC) subjects (48±10yrs). CD patients and NC were submitted to STE and CD patients were submitted to cardiac magnetic resonance (CMR) with late gadolinium administration to detect cardiac fibrosis by the late enhancement technique. Global longitudinal strain (GLS), circumferential (GCS) and radial strain (GRS) were defined as the average of segments measured from three apical view (GLS) and short axis views (GRS and GCS). Regional left ventricular (LV) longitudinal strain (Reg LS) was measured from each of the 17 segments. Twist was measured as systolic peak difference between basal and apical rotation and indexed to LV length to express torsion. RESULTS: STE global indices (GLS, GCS, twist and torsion) were reduced in CCC vs NC (GLS: -14±6.3% vs -19.3±1.6%, p = 0.001; GCS: -13.6±5.2% vs -17.3 ±2.8%; p = 0.008; twist: 8±7° vs 14±7°, p = 0.01 and torsion: 0.96±1°/cm vs 1.9±1°/cm, p = 0.005), but showed no differences in IFCD vs NC. RegLS was reduced in IFCD vs NC in four LV segments: basal-inferior (-16.3±3.3% vs -18.6±2.2%, p = 0.013), basal inferoseptal (-13.1±3.4 vs -15.2±2.7, p = 0.019), mid-inferoseptal (-17.7±3.2 vs -19.4±2, p = 0.032) and mid-inferolateral (-15.2±3.5 vs -17.8±2.8, p = 0.014). These abnormalities in RegLS occurred in the absence of myocardial fibrosis detectable with CMR in nearly 92% of subjects with IFCD, while myocardial fibrosis was present in 65% with CCC. CONCLUSION: RegLS detects early regional impairment of myocardial strain that is independent from fibrosis in IFCD subjects., Author summary Regional longitudinal strain is reduced in IFCD before significant fibrosis. As CD progresses to CF, global STE measurements of left ventricle (GLS, GCS, twist and torsion) and GLS of right ventricle are reduced. Early abnormal strain pattern of CD comprises inferior, septoinferior and inferolateral segments of LV. Recognizing the regional strain pattern of Chagas cardiomyopathy may help identifying the disease even at early stages.

Key Points Question What is the risk of developing cardiomyopathy among patients with the acute phase of Chagas infection or the indeterminate chronic form of Chagas disease? Findings In this systematic review and meta-analysis of 32 studies of patients with Chagas disease, the pooled estimated annual rate of cardiomyopathy was 4.6% among patients with acute Chagas infection and 1.9% among patients with indeterminate chronic Chagas disease. Meaning The findings indicate that asymptomatic individuals with indeterminate chronic Chagas disease without cardiac injury and individuals with acute Chagas infection may have a significant risk of developing chronic cardiomyopathy., Importance Chagas cardiomyopathy is associated with substantial morbidity and mortality. Precise estimates of the risk of developing cardiomyopathy among patients with the acute or indeterminate chronic forms of Chagas disease are lacking. Objective To estimate the risk of developing chronic cardiomyopathy in patients with acute and indeterminate chronic forms of Chagas disease. Data Sources A systematic search in the Cochrane Library, Embase, Latin American and Caribbean Health Sciences Literature (LILACS), Medline, and Web of Science Core Collection databases was conducted from October 8 to October 24, 2018. Studies published between January 1, 1946, and October 24, 2018, that were written in the English, Spanish, and Portuguese languages were included. Search terms included Chagas disease; development of cardiomyopathy; latency duration; and determinants of the Chagas latency period. Study Selection Longitudinal observational studies of participants diagnosed with the acute phase of Chagas infection or the indeterminate chronic form of Chagas disease who were followed up until the development of cardiomyopathy were included. Studies were excluded if they did not provide sufficient outcome data. Of 10 761 records initially screened, 32 studies met the criteria for analysis. Data Extraction and Synthesis Critical appraisals of studies were performed using checklists from the Joanna Briggs Institute Reviewer’s Manual, and data were collected from published studies. A random-effects meta-analysis was used to obtain pooled estimated annual rates. Data were analyzed from September 11 to December 4, 2019. This study followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline for the registration of the protocol, data collection and integrity, assessment of bias, and sensitivity analyses. Main Outcomes and Measures Main outcomes were defined as the composite of the development of any new arrhythmias or changes in electrocardiogram results, dilated cardiomyopathy and segmental wall motion abnormalities in echocardiogram results, and mortality associated with Chagas disease. Results A total of 5005 records were screened for eligibility. Of those, 298 full-text articles were reviewed, and 178 of those articles were considered for inclusion in the quantitative synthesis. After exclusions, 32 studies that included longitudinal observational outcomes were selected for the analysis; 23 of those studies comprised patients with the indeterminate chronic form of Chagas disease, and 9 of those studies comprised patients in the acute phase of Chagas infection. The analysis indicated that the pooled estimated annual rate of cardiomyopathy development was 1.9% (95% CI, 1.3%-3.0%; I2 = 98.0%; τ2 [ln scale] = 0.9992) in patients with indeterminate chronic Chagas disease and 4.6% (95% CI, 2.7%-7.9%; I2 = 86.6%; τ2 [ln scale] = 0.4946) in patients with acute Chagas infection. Conclusions and Relevance Patients with the indeterminate chronic form of Chagas disease had a significant annual risk of developing cardiomyopathy. The annual risk was more than double among patients in the acute phase of Chagas infection., This systematic review and meta-analysis assesses the risk of developing chronic cardiomyopathy among patients with acute and indeterminate chronic forms of Chagas disease.

OBJECTIVES This study was designed to investigate digestive and heart associations, using esophageal transit scintigraphy in three different groups: patients exclusively with the dilated cardiac form of Chagas disease (DCCh), an indeterminate form of Chagas disease, and healthy controls. As a hypothesis, we assumed that autonomic chagasic denervation is a global process. MATERIALS AND METHODS Twenty healthy controls and 75 outpatients with Chagas disease, divided into indeterminate form (n = 33) and (DCCh, n = 42), underwent esophageal scitigraphy. The esophageal transit time (ETT) and percentage of esophageal emptying (%EE) were analyzed by group and correlated with left ventricular ejection fraction (LVEF). RESULTS ETT alterations were found in 57% of indeterminate form and 80% of DCCh. The observed values of ETT and %EE in Chagas disease groups were significantly different from the controls (P-value

Background Atrial fibrillation (AF) carries ominous consequences in patients with Chagas disease. The aim of this study was to determine whether left atrial (LA) volume and function assessed using three-dimensional echocardiographic (3DE) imaging and two-dimensional speckle-tracking echocardiographic deformation analysis of strain (e) could predict new-onset AF in patients with Chagas disease. Methods A total of 392 adult patients with chronic Chagas disease (59% women; mean age, 53 ± 11 years) who underwent echocardiography were consecutively enrolled in this prospective longitudinal study. Echocardiographic evaluation included two-dimensional (2D) Doppler echocardiography, with evaluation of left ventricular systolic and diastolic function, LA size, and LA and left ventricular function on 3DE and e analyses. Multivariate Cox proportional-hazards regression analysis models adjusting for age, sex, hypertension, presence of a pacemaker, and 2D Doppler echocardiographic parameters were used to test if the variables of interest had independent prognostic value for AF prediction. Results Patients with Chagas disease were followed for 5.6 ± 2.7 years. Among these, 139 (35.5%) had the indeterminate form, 224 (57.1%) had the cardiac form, five (1.3%) had the digestive form, and 24 (6.1%) had the cardiodigestive form. The study end point of AF occurred in 45 patients. Total LA emptying fraction (hazard ratio, 0.93; 95% CI, 0.89–0.98; P = .002), passive LA emptying fraction (HR, 0.95; 95% CI, 0.91–0.99; P = .02), and peak negative global LA e (HR, 1.22; 95% CI, 1.05–1.41; P = .01) were predictors of new-onset AF independent of clinical and 2D Doppler echocardiographic parameters. Conclusions LA function assessed on 3DE and e analyses predicts new-onset AF in patients with Chagas disease independent of clinical and 2D Doppler echocardiographic indexes.

Introduction According to the WHO, Chagas disease affects 8 to 10 million people, mainly in the Americas and in some European countries, with more than 10 thousand annual deaths. It presents an acute phase followed by a chronic, categorized as indeterminate, cardiac or digestive forms. After infestation, most patients remain asymptomatic, but 40% progress to symptomatic form at the rate of 1.8 to 5% patients/year. Evidence of myocardial fibrosis in 41% of these patients was found by magnetic resonance imaging. Objective To evaluate, by echocardiography, patients with Chagas disease, indeterminate phase, analysing dimensions, function and parameters of deformation and mechanical dispersion in left and right cardiac cavities. Method The study included 44 asymptomatic patients, 36 female, mean age 51 ± 10 years with positive Chagas serology and a control group of 44 healthy individuals, 35 female, mean age 52 ± 10 years. Left and right cavitary dimensions were evaluated, systolic and diastolic function, global myocardial deformation and mechanical dispersion. The groups were compared by the paired "t" test with significance level Results Demographic data (age, body surface area) with no significant differences. Left ventricular (LV) diameters (p Conclusion Asymptomatic patients with Chagas disease (undetermined phase), when compared with healthy individuals of the same age group, presented larger cavitary diameters, diastolic disfunction and, deformation parameters of the left and right ventricles, with increased mechanical dispersion in both chambers. These data seem to corroborate recent results obtained by magnetic resonance imaging with gadolinium, suggesting areas of myocardial fibrosis in these patients.

The paper considers theoretical explanation and construction of some mathematical models of a transportation mean operational process in reference to maintenance optimal periodicity. The important finding is that the objectively existing engineering transportation means maintenance optimal periodicity is determined in the different from the probabilistic methods way. There is a scientifically proven explanation for the mentioned above periodicity optimization with the help of the specially introduced hybrid-optional effectiveness functions distribution. The developed doctrine uses the entropy paradigm conditional extremization approach. This contribution allows obtaining the wanted optimal periodicities sidestepping the related states probabilities determination and their further extremization. The essential breakthrough of the developed doctrine is that the optional objective effectiveness functions, in such a case, are the corresponding combinations of the intensities of the studied system’s possible transitions from state to state, which relates with the set of the considered operational options. Corresponding limit solutions for the zero-to-zero ratio indeterminate forms are analyzed. Theoretical speculations are illustrated with the example calculation experiments. The necessary diagrams are plotted.

Este artigo parte do conceito de democracia como forma indeterminada de poder, em um esforço para pensar o sentido concreto da organização social orientada pela democracia, assim compreendida. A democracia parece admitir tanto uma organização material socialista quanto liberal. Daí a necessidade de distinguir o nível formal de abertura democrática e o nível material de luta por hegemonia em que essa alternativa aparece, entendendo ambos como determinações contingentes em disputa.

We apply the squeeze theorem, instead of L′Hospital′s rule, to evaluate limits in indeterminate form of exponential type. We do not require differentiability, instead needing the boundedness of a q...

INTRODUCTION In order to detect Trypanosoma cruzi and determine the genetic profiles of the parasite during the chronic phase of Chagas disease (ChD), parasitological and molecular diagnostic methods were used to assess the blood of 91 patients without specific prior treatment. METHODS Blood samples were collected from 68 patients with cardiac ChD and 23 patients with an indeterminate form of ChD, followed by evaluation using blood culture and polymerase chain reaction. T . cruzi isolates were genotyped using three different genetic markers. RESULTS: Blood culture was positive in 54.9% of all patients, among which 60.3% had the cardiac form of ChD, and 39.1% the indeterminate form of ChD. There were no significant differences in blood culture positivity among patients with cardiac and indeterminate forms. Additionally, patient age and clinical forms did not influence blood culture results. Polymerase chain reaction (PCR) was positive in 98.9% of patients, although comparisons between blood culture and PCR results showed that the two techniques did not agree. Forty-two T . cruzi stocks were isolated, and TcII was detected in 95.2% of isolates. Additionally, one isolate corresponded to TcIII or TcIV, and another corresponded to TcV or TcVI. CONCLUSIONS Blood culture and PCR were both effective for identifying T. cruzi using a single blood sample, and their association did not improve parasite detection. However, we were not able to establish an association between the clinical form of ChD and the genetic profile of the parasite.

A mixed batch of sea cucumbers tentatively labelled as ?Thyone or ?Havelockia species was obtained on loan from the Natural History Museum, United Kingdom (NHMUK) for identifications and records. The material dates back to 1850 and originates from shallow waters from various parts of the world. The material includes two new species and one new subspecies which have already been described in an earlier paper (see Thandar, 2017). The remaining specimens comprise a few known or poorly known nominal species and several indeterminate forms. This paper describes the known species while adding some useful information about them. Of the indeterminate species included are several specimens most belonging to the genus Thyone or Havelockia which, because of their incompleteness and absence of ossicles, are not identified beyond their suspected genus or species.

We have considered in the previous lecture the functions of the variable x, which, for a particular value of the variable, are presented under the indeterminant form \( \frac{0}{0}. \ \) It often happens that this form is found replaced by one of the following

Chagas disease (CD) is highly endemic in Latin America, and has been emerging in developed countries. Early diagnosis of left ventricular (LV) systolic dysfunction, routinely done by echocardiography, is crucial for therapy. Speckle tracking echocardiography allows determination of LV segmental rotations, twist/torsion, and this analysis may disclose an unapparent myocardial contractile deficit in initial stages of CD. Therefore, this study aimed to highlight a possible unapparent myocardial contractile deficit in CD indeterminate form (IF) by a comprehensive torsional mechanics analysis. Patients with CDIF diagnosis, initial chagasic cardiomyopathy (CCMP characterized by ECG abnormalities and LVEF > 0.55), and normal controls were prospectively enrolled, and underwent conventional echocardiogram with images acquisition for STE offline analysis. Target parameters were basal and apical rotations, and calculation of twist and torsion. A total of 42 patients were included (CDIF, eight; CCMP, 13; and 21 controls). Chagasic patients had a mean age of 55 years, five (24 %) men, and controls, 50 years, seven (33 %) men. Torsional mechanics analyzes resulted in no significant difference in all parameters studied between groups. Twist in CDIF was 20.8° ± 6.5°; CCMP, 19.0° ± 3.5° and controls, 19.7° ± 3.7° (p = 0.67). Torsion in CDIF was 2.6° ± 0.8°; CCMP, 2.4° ± 0.6° and controls, 2.4° ± 0.5° (p = 0.63). Patients with Chagas disease have no abnormalities in torsional mechanics during its indeterminate and initial cardiomyopathy stages.

This study investigates the effectiveness of a teaching activity that aimed to convey the meaning of indeterminate forms to a group of undergraduate students who were enrolled in an elementary mathematics education programme. The study reports the implementation sequence of the activity and students’ experiences in the classroom. To assess the effectiveness of the adopted approach, an individual homework assignment, in which students were asked to generate examples for indeterminate forms as geometrical constructions, was applied. The findings revealed that the students had various misunderstandings about the meanings of indeterminate forms prior to the study. Moreover, the use of the term “indeterminate” to designate these limit forms was found to be inappropriate because of its connotation. In light of the results, some suggestions are made to improve the teaching of indeterminate forms. Key words: Calculus teaching, indeterminate forms, limit concept, concept of infinity.

The aim of this work is to regularize the expression of the coefficients, expressed in term of trigonometrical or hyperbolic functions, arising from the exponential fitting procedure, by reformulating them in terms of the so-called ηm functions. These coefficients are functions of the variable ν = ωh where ω is the frequency and h is the step size. This reformulation eliminates the 0/0 indeterminate form of the coefficients when ν tends to 0. This procedure makes the methods more accurate. A numerical evidence is also given.

Most patients with chronic Chagas disease (CD) present the indeterminate form and are at risk to develop the cardiac form. However, the actual rate of progression to the cardiac form is still unknown. Methods: In total, 550 patients with the indeterminate CD form were followed by means of annual electrocardiogram at our outpatient clinic. The studied endpoint was progression to cardiac form defined by the appearance of electrocardiographic changes typical of CD. The progression rate was calculated as the cumulative progression rate and the incidence progression rate per 100 patient years. Results: Thirty-seven patients progressed to the CD cardiac form within a mean of 73 ± 48 months of follow-up, which resulted in a 6.9% cumulative progression rate and incidence rate of 1.48 cases/100 patient years. Patients who progressed were older (mean age 47.8 ± 12.2 years), had a higher prevalence of associated heart diseases (p < 0.0001), positive xenodiagnosis (p = 0.007), and were born in the most endemic Brazilian states (p = 0.018). Previous co-morbidities remained the only variable associated with CD progression after multivariate Cox proportional hazards regression analysis (p = 0.002). Conclusion: The progression rate to chronic CD cardiac form is low and inferior to rates previously reported in other studies.

Objective: Accumulating evidence indicates that zero divided by zero is equal to one. Still it is not clear what number theory or algebra is saying about this. Methods: To explore the relationship between the problem of the division of zero by zero and number theory, a systematic approach is used while analyzing the relationship between number theory and independence. Result: The theorems developed in this publication support the thesis that zero divided by zero is equal to one. Furthermore, it was possible to define the law of independence under conditions of number theory and algebra. Conclusion: The findings of this study suggest that zero divided by zero equals one.

Transforming growth factor β1 (TGF-β1) is an important mediator in Chagas disease. Furthermore, patients with higher TGF-β1 serum levels show a worse clinical outcome. Gene polymorphism may account for differences in cytokine production during infectious diseases. We tested whether TGFB1 polymorphisms could be associated with Chagas disease susceptibility and severity in a Brazilian population. We investigated five single-nucleotide polymorphisms (−800 G>A, −509 C>T, +10 T>C, +25 G>C, and +263 C>T). 152 patients with Chagas disease (53 with the indeterminate form and 99 with the cardiac form) and 48 noninfected subjects were included. Genotypes CT and TT at position −509 of the TGFB1 gene were more frequent in Chagas disease patients than in noninfected subjects. Genotypes TC and CC at codon +10 of the TGFB1 gene were also more frequent in Chagas disease patients than in noninfected subjects. We found no significant differences in the distribution of the studied TGFB1 polymorphisms between patients with the indeterminate or cardiac form of Chagas disease. Therefore, −509 C>T and +10 T>C TGFB1 polymorphisms are associated with Chagas disease susceptibility in a Brazilian population.

INTRODUCTION: We investigated the occurrence of coronary sinus abnormalities in the indeterminate form of Chagas disease (CD). METHODS: Differences between the maximum and minimum diameters of the coronary sinus (∆%) on echocardiography were evaluated in individuals with the indeterminate form of CD (n=14) and those without (n=16) CD. The association of the difference with abnormalities detected by echocardiography and myocardial scintigraphy was assessed. RESULTS: The mean Δ% values did not differ significantly between the groups. There was no correlation of the measurements with echocardiographic and myocardial scintigraphy findings. CONCLUSIONS: The coronary sinus evaluation revealed no differences between the groups.