Molecular identification of Trypanosoma cruzi discrete typing units in end-stage chronic Chagas heart disease and reactivation after heart transplantation

BACKGROUND

One hundred years after the discovery of Chagas disease, it remains a major neglected tropical disease. Chronic Chagas heart disease (cChHD) is the most severe manifestation. Heart transplantation is the proper treatment for end-stage heart failure, although reactivation of disease may result after receipt of immunosuppressive therapy. T. cruzi strains cluster into 6 discrete typing units (DTUs; I-VI) associated with different geographical distribution, transmission cycles and varying disease symptoms. In the southern cone of South America, T. cruzi II, V, and VI populations appear to be associated with Chagas disease and T. cruzi I with sylvatic cycles.

METHODS

Molecular characterization of DTUs, T. cruzi I genotypes (on the basis of spliced-leader gene polymorphisms), and minicircle signatures was conducted using cardiac explant specimens and blood samples obtained from a cohort of 16 Argentinean patients with cChHD who underwent heart transplantation and from lesion samples obtained from 6 of these patients who presented with clinical reactivation of Chagas disease.

RESULTS

Parasite persistence was associated with myocarditis progression, revealing T. cruzi I (genotype Id) in 3 explant samples and T. cruzi II, V, or VI in 5 explant samples. Post-heart transplantation follow-up examination of bloodstream DTUs identified T. cruzi I in 5 patients (genotypes Ia or Id) and T. cruzi II, V, or VI in 7 patients. T. cruzi I, V, and VI were detected in skin chagoma specimens, and T. cruzi V and VI were detected in samples obtained from patients with myocarditis reactivations. Multiple DTUs or genotypes at diverse body sites and polymorphic minicircle signatures at different cardiac regions revealed parasite histotropism. T. cruzi I infections clustered in northern Argentina (latitude, 23 degrees S-27 degrees S), whereas T. cruzi II, V, or VI DTUs were more ubiquitous.

CONCLUSIONS

Multiple DTUs coexist in patients with Chagas disease. The frequent finding of T. cruzi I associated with cardiac damage was astounding, revealing its pathogenic role in cChHD at the southern cone.

1,2,5-Oxadiazole N-oxide derivatives and related compounds as potential antitrypanosomal drugs: structure-activity relationships

The syntheses of a new series of derivatives of 1,2,5-oxadiazole N-oxide, benzo[1,2-c]1,2,5-oxadiazole N-oxide, and quinoxaline di-N-oxide are described. In vitro antitrypanosomal activity of these compounds was tested against epimastigote forms of Trypanosoma cruzi. For the most effective drugs, derivatives IIIe and IIIf, the 50% inhibitory dose (ID50) was determined as well as their cytotoxicity against mammalian fibroblasts. Electrochemical studies and ESR spectroscopy show that the highest activities observed are associated with the facile monoelectronation of the N-oxide moiety. Lipophilic-hydrophilic balance of the compounds could also play an important role in their effectiveness as antichagasic drugs.

Differential expression of a virulence factor, the trans-sialidase, by the main Trypanosoma cruzi phylogenetic lineages

The clinical outcome of Chagas disease is highly variable, mainly because of the heterogeneity of Trypanosoma cruzi, a parasite for which 2 major phylogenetic groups (I and II) were recently defined. Epidemiological and immunological data indicate that the prevalence of T. cruzi II in patients living in the southern cone of South America correlates with the alterations caused by Chagas disease. We report here that infection with T. cruzi II isolates induces 100% mortality in mice, in contrast to infection with T. cruzi I isolates, in which almost all mice enter the chronic phase even when a 1000-fold higher inoculum is administered. Trypomastigotes from T. cruzi II strains express and shed significantly higher amounts of trans-sialidase than do those from the T. cruzi I lineage. Disorganization of the thymus histoarchitecture associated with the circulating enzyme was observed after infection with T. cruzi II strains, in contrast to transient thymus lesions found in mice infected with T. cruzi I strains. Therefore, trans-sialidase becomes the first T. cruzi virulence factor identified that is differentially expressed by the main parasite groups and that contributes to their contrasting behaviors.

Synthesis and antitrypanosomal evaluation of E-isomers of 5-nitro-2-furaldehyde and 5-nitrothiophene-2-carboxaldehyde semicarbazone derivatives. structure-activity relationships

Several novel semicarbazone derivatives were prepared from 5-nitro-2-furaldehyde or 5-nitrothiophene-2-carboxaldehyde and semicarbazides bearing a spermidine-mimetic moiety. All derivatives presented the E-configuration, as determined by NMR-NOE experiments. These compounds were tested in vitro as potential antitrypanosomal agents, and some of them, together with the parent compounds, 5-nitro-2-furaldehyde and 5-nitrothiophene-2-carboxaldehyde semicarbazone derivatives, were also evaluated in vivo using infected mice. Structure-activity relationship studies were carried out using voltammetric response and lipophilic-hydrophilic balance as parameters. Two of the compounds (1 and 3) displayed the highest in vivo activity. A correlation was found between lipophilic-hydrophilic properties and trypanocidal activity, high R(M) values being associated with low in vivo effects.

Comparison of two prognostic models for acute pulmonary embolism: clinical vs. right ventricular dysfunction-guided approach

BACKGROUND

Recently, some prognostic models for acute pulmonary embolism (PE) have been proposed. We investigated whether the Pulmonary Embolism Severity Index (PESI) and the European Society of Cardiology (ESC) prognostic approaches result in different prognoses.

METHODS

Consecutive adult patients with acute PE were included. According to the ESC guidelines, high-risk patients were identified by the presence of shock/hypotension, intermediate-risk patients by elevated troponin I or right ventricular dysfunction as assessed by echocardiography, and low-risk patients by the absence of any of the above. In the PESI model, 11 clinical variables, easily accessible at the bedside, were used to generate three risk classes. The main outcomes were all-cause and PE-related in-hospital mortality.

RESULTS

Forty-one patients (8%, 95% confidence interval [CI] 5.8-10.8) of 510 died. According to the ESC model, 40% were at low risk of short-term mortality, 54% at intermediate risk, and 6% at high risk. The distribution according to the PESI model was 31% (P < 0.05 vs. ESC), 49% and 20% (P < 0.05 vs. ESC), respectively. Mortality increased through the risk classes (P < 0.01), without significant differences between the models. The ESC model identified with higher accuracy than the PESI model both high-risk and low-risk patients (P < 0.05 for both). When patients with shock/hypotension were excluded, the PESI model stratified patients into classes with increasing PE-related mortality (0.7%, 4.3%, and 11.6%, P < 0.05). Troponin I and right ventricular dysfunction added incremental prognostic value to the PESI model, particularly in normotensive patients at intermediate risk.

CONCLUSIONS

The ESC model showed higher accuracy than the PESI model in identifying high-risk and low-risk patients. In normotensive patients, the PESI model could guide clinical management as well as troponin I and echocardiography testing.

The trans-sialidase from Trypanosoma cruzi triggers apoptosis by target cell sialylation

The trans-sialidase, a modified sialidase that transfers sialyl residues among macromolecules, is a unique enzymatic activity expressed by some parasitic trypanosomes being essential for their survival in the mammalian host and/or in the insect vector. The enzyme from Trypanosoma cruzi, the agent of Chagas disease, is found in blood and able to act far from the infection site by inducing apoptosis in cells from the immune system. A central and still unsolved question is whether trans-sialidase-mediated addition or removal of sialic acid to/from host acceptor molecules is the event associated with the apoptosis induced by the enzyme. Here we show that lactitol, a competitive inhibitor that precluded the transference of the sialyl residue to endogenous acceptors but not the hydrolase activity of the enzyme, prevented ex vivo and in vivo the apoptosis caused by the trans-sialidase. By lectin histochemistry, the transference of sialyl residue to the cell surface was demonstrated in vivo and found associated with the apoptosis induction. The sialylation of the CD43 mucin, a key molecule involved in trans-sialidase-apoptotic process, was readily detected and also prevented by lactitol on thymocytes. Therefore, lesions induced by trans-sialidase on the immune system are due to the sialylation of endogenous acceptor molecules.

Severe aplastic anaemia: correlation of in vitro test with clinical response to immunosuppression in 20 patients

Colony formation in agar (CFU-c) was studied in 20 patients with severe aplastic anaemia by three different assays: (1) cultures of light density untreated marrow cells; (2) cultures of marrow cells manipulated in order to enhance colony formation (pretreatment with antilymphocytic globulin, ALG, or 6-methylprednisolone, 6-MPr, T cell depletion, adherent cell (AC) depletion, depletion of both AC and T cells), and (3) co-culture of putative suppressor T cells with autologous T-depleted marrow cells. By the first assay, all patients showed poor colony formation (1 +/- 1.5 colonies/10(5) cells; normal controls 46 +/- 18 colonies/10(5) cells). By the second assay, ALG and 6-MPr had no significant effect on colony formation. Removal of adherent cells proved equally without effect on colony growth. On the contrary, removal of T cells enhanced significantly (P less than 0.001) colony formation in 10 out of 20 patients. By the third assay, colony formation of marrow cells (deprived of T lymphocytes) was inhibited by the addition of autologous T cells in six patients studied. All patients were given high dose bolus 6-MPr as first treatment on admission: only patients who had detectable suppressor T cells in their marrow achieved a complete autologous haematologic reconstitution after 6-MPr or after 6-MPr and ALG. The results of this study indicate the detection of CFU-c/suppressor T cells correlates with responses to immunosuppressive regimens, and may thus help to identify patients with immune mediated aplastic anaemia.

1,2,5-Oxadiazole N-oxide derivatives as potential anti-cancer agents: synthesis and biological evaluation. Part IV

Several new 1,2,5-oxadiazole N-oxide derivatives and some deoxygenated analogues were synthesized to be tested as potential selective hypoxic cell cytotoxins. Compounds prepared were designed in order to gain insight into the mechanism of action of this kind of cytotoxin. Compounds were tested in oxia and hypoxia and they proved to be non-selective. 3-Cyano-N(2)-oxide-4-phenyl-1,2,5-oxadiazole showed the best cytotoxic activity in oxia. The cytotoxicity observed for these derivatives could be explained in terms of the electronic characteristics of the 1,2,5-oxadiazole substituents. Electrochemical and ESR studies were performed on the more cytotoxic derivative.

Strongyloidiasis Outside Endemic Areas: Long-term Parasitological and Clinical Follow-up After Ivermectin Treatment

BACKGROUND

Strongyloides stercoralis affects 30-100 million people worldwide. The first-line therapy is ivermectin. Cure is defined as the absence of larvae by parasitological methods 1 year after treatment. To date, no longitudinal parasitological studies for longer periods of time have been conducted to confirm its cure. Here, we evaluated treatment response in long-term follow-up patients with chronic infection using parasitological and molecular methods for larvae or DNA detection.

METHODS

A prospective, descriptive, observational study was conducted between January 2009 and September 2015 in Buenos Aires, Argentina. Twenty-one patients with S. stercoralis diagnosis were evaluated 30, 60, and 90 days as well as 1, 2, 3, and/or 4 years after treatment by conventional methods (fresh stool, Ritchie method, agar plate culture), S. stercoralis-specific polymerase chain reaction (PCR) in stool DNA, and eosinophil values.

RESULTS

During follow-up, larvae were detected by conventional methods in 14 of 21 patients. This parasitological reactivation was observed starting 30 days posttreatment (dpt) and then at different times since 90 dpt. Eosinophil values decreased (P = .001) 30 days after treatment, but their levels were neither associated with nor predicted these reactivations. However, S. stercoralis DNA was detected by PCR in all patients, both in their first and subsequent stool samples, thus reflecting the poor efficacy of ivermectin at eradicating parasite from host tissues. Asymptomatic eosinophilia was the most frequent clinical form among chronically infected patients.

CONCLUSIONS

These results suggest that the parasitological cure is unlikely. Strongyloidiasis must be considered a chronic infection and ivermectin administration schedules should be reevaluated.

4-Demethoxydaunorubicin (Idarubicin) in refractory or relapsed acute leukemias. A pilot study

Twenty-five adults with previously treated acute leukemia were treated with 4-demethoxydaunorubicin (Idarubicin) with a daily dose of 8 mg/m2 for 3 days intravenously. Complete remission was achieved in 3 of 18 patients with acute nonlymphoblastic leukemia (ANLL) and 2 of 6 with lymphoblastic leukemia. Complete remissions were observed in two of eight ANLL patients refractory to cytarabine, anthracycline, and m-Amsa (amsacrine), indicating a lack of cross-resistance between these drugs and Idarubicin. The median duration of remission was 8 weeks. The main major toxicity of Idarubicin therapy, severe myelosuppression, cannot be considered a toxic effect because it was desired in this case list. Our preliminary results indicate that Idarubicin has significant activity against refractory adult acute leukemia.

Differential distribution of genes encoding the virulence factor trans-sialidase along Trypanosoma cruzi Discrete typing units

Trypanosoma cruzi the agent of Chagas disease is a monophyletic but heterogeneous group conformed by several Discrete Typing Units (DTUs) named TcI to TcVI characterized by genetic markers. The trans-sialidase (TS) is a virulence factor involved in cell invasion and pathogenesis that is differentially expressed in aggressive and less virulent parasite stocks. Genes encoding TS-related proteins are included in a large family divided in several groups but only one of them contains TS genes. Two closely related genes differing in a T/C transition encode the enzymatically active TS (aTS) and a lectin-like TS (iTS). We quantified the aTS/iTS genes from TcII and TcVI aggressive and TcI low virulent strains and found variable aTS number (1-32) per haploid genome. In spite of being low TS enzyme-expressers, TcI strains carry 28-32 aTS gene copies. The intriguing absence of iTS genes in TcI strains together with the presence of aTS/iTS in TcII and TcVI strains (virulent) were observed. Moreover, after sequencing aTS/iTS from 38 isolates collected along the Americas encompassing all DTUs, the persistent absence of the iTS gene in TcI, TcIII and TcIV was found. In addition, the sequence clustering together with T/C transition analysis correlated to DTUs of T. cruzi. The consistence of TS results with both evolutionary genome models proposed for T. cruzi, namely the "Two Hybridization" and the "Three Ancestor" was discussed and reviewed to fit present findings. Parasite stocks to attempt genetic KO or to assay the involvement of iTS in parasite biology and virulence are finally available.

Immune system pathogenesis is prevented by the neutralization of the systemic trans-sialidase from Trypanosoma cruzi during severe infections

During the acute phase of Trypanosoma cruzi infection, strong haematological and immune system alterations are observed. The parasite expresses trans-sialidase, a virulence factor responsible for the sialylation of its surface glycoconjugates. This enzyme is also shed to the bloodstream where it is associated with immune system alterations triggered during the infection. During experimental and human infections, the host elicits antibodies able to neutralize the enzyme activity that would be responsible for restricting systemic trans-sialidase to the early steps of the infection, when major immune alterations are induced. The actual relevance of these antibodies was tested by passive transference of monoclonal neutralizing antibodies in acute infection models displaying extreme sensitivity to the infection. Mice were inoculated with virulent parasite strains that induce high parasitaemia, early mortality and strong immune tissue abnormalities. The trans-sialidase-neutralizing antibodies were able to preserve B cell areas both in ganglia and spleen as well as the thymus architecture even in these extreme models. Although no differences between control and treated mice regarding animal survival were found, a major role for the humoral response in controlling the damage of the immune system induced by a systemically distributed virulence factor was defined in an infection with a eukaryotic pathogen.

Immunological identification of Trypanosoma cruzi lineages in human infection along the endemic area

Genotyping studies show a polarized geographic distribution of Trypanosoma cruzi lineages in humans. Here, we assessed their distribution along Latin America through an immunological approach we designated Western blot (WB) assay with Trypomastigote small-surface antigen (TSSA) I and TSSA II (TSSA-WB). These antigens are expressed by T. cruzi I (TCI; now TcI) and T. cruzi II (TCII; reclassified as TcII to TcVI) parasites. TSSA-WB showed good concordance with genotyping tests. An unexpected frequency of TSSA II recognition was observed in Colombia, Venezuela, and Mexico (northern region of Latin America). In Argentina and Paraguay (southern region), immunophenotyping confirmed the already reported TCII (TcII to TcVI) dominance. The lineage distribution between these regions showed significant difference but not among countries within them (except for Colombia and Venezuela). TSSA-WB shows TCII emergence in the northern region where TCI was reported as dominant or even as the unique T. cruzi lineage infecting humans.

Acute myelomonocytic leukemia. Demonstration of pulmonary involvement by bronchoalveolar lavage

Massive pulmonary infiltration by leukemic cells resulting in respiratory symptoms is a rare complication of acute leukemia. We report the findings in a patient with acute myelomonocytic leukemia presenting with acute onset of fever, dyspnea, and nonproductive cough, in whom the diagnosis of pulmonary invasion by leukemic cells was made by cytochemical analysis of bronchoalveolar cells recovered by lavage.

Alpha-interferon as induction and maintenance therapy in hairy cell leukemia: a long-term follow-up analysis

Although in recent years the use of purine analogues has increased the percentage of long-term complete response the effect on overall survival of patients with hairy cell leukemia (HCL) is not yet clear. This study aimed to evaluate the long-term outcome (mean follow up of 92 months) of 64 patients receiving IFN as first-line therapy. IFN was well tolerated and effective. The overall response rate was 91% (PR 65%, CR 13%, GPR 13%). Forty-one patients (63%) received IFN 3 MU/ wk as maintenance therapy. The 10-yr projected survival rate of responding patients (CR and GPR 100%; PR 95%) and non-responders (SD, PD 80%) clearly shows that type of response does not affect survival. Patients receiving IFN maintenance had a statistically higher PFS than those who did not (p <0.01). This study shows that IFN is still one of the standard therapies for this disease, that achieving CR has no primary relevance for the control of the disease, and that good utilization of therapeutic resources may assure HCL patients a survival rate comparable to that of a normal, healthy population.

Improved outcome in young adults with de novo acute myeloid leukemia in first remission, undergoing an allogeneic bone marrow transplant

We assessed the outcome of 170 patients with AML in first complete remission, aged 1-47 years (median 29), who had undergone an allogeneic BMT before or after 1990 (n=80 and n=90, respectively); all patients were prepared with cyclophosphamide and TBI; the median follow-up for surviving patients was 13 years. The donor was an HLA-identical sibling in 164 patients. Transplant-related mortality (TRM) was 30% before and 7% after 1990 (P<0.001); relapse-related death (RRD) was 26 and 11% (P=0.002); and actuarial 10-year survival was 42 and 79% (P<0.00001). Patients transplanted after 1990 were older, had a shorter interval diagnosis-BMT, had less FAB-M3 cases, received a higher dose of TBI, a higher marrow cell dose and combined (cyclosporine+methotrexate) GVHD prophylaxis. Patients relapsing after transplant had an actuarial survival of 0 vs 31% if grafted before or after 1990 (P=0.01), and their median follow-up exceeds 10 years. In conclusion, the overall survival of first remission AML undergoing an allogeneic BMT has almost doubled in the past two decades, despite older age and fewer M3 cases. Improvement has come not only from changes in transplant procedures, but also from effective rescue of patients relapsing after transplant.

Antibody maturation in Trypanosoma cruzi-infected rats

The study of antibody avidity changes during infection has improved the understanding of the pathologic processes involved in several infectious diseases. In some infections, like toxoplasmosis, this information is being used for diagnostic purposes. Results of the evolution of antibody avidity for different specific antigens in Trypanosome cruzi-infected rats are presented. A Western blotting technique, combined with avidity analysis to identify antigens that elicit high-avidity antibodies, is suggested. In this system, antibodies showed high avidity values only during the chronic phase of infection and only in relation to antibodies against 21-, 33-, 41-, 42-, 56-, 58-, 66-, and 72-kDa antigens. Finally, a 97-kDa T. cruzi antigen, which was recognized by high-avidity antibodies and occurred in noninfected rats, was identified. These results allow us to evaluate the different antigens in chagasic infection. Our results show that with the correct choice of antigen it is possible to detect differences in maturation of antibodies and to discriminate, in an experimental model, between recent (acute) and chronic infections.

Synthesis and biological evaluation of 1,2,5-oxadiazole N-oxide derivatives as potential hypoxic cytotoxins and DNA-binders

Several new 1,2,5-oxadiazole N-oxide derivatives were synthesized to be tested both as potential selective hypoxic cell cytotoxins and as DNA-binding agents. The compounds prepared included bis(1,2,5-oxadiazole N-oxide) derivatives and oxadiazole rings linked to naphthyl residues. The compounds were tested for their cytotoxicity in oxia and hypoxia and they proved to be non-selective and less active than the parent compounds 3-formyl-4-phenyl-1,2,5-oxadiazole N2-oxide (3) and 3-chloromethyl-4-phenyl-1,2,5-oxadiazole N2-oxide (4). The DNA-affinity assays showed that the compounds tested have poor affinity for this biomolecule.

Delusions of witchcraft: a cross cultural study

Since the Second World War the number of Italians working in Switzerland has greatly increased. In 1962 there were officially 454,000 Italian workers in that country and this is almost certainly an underestimate. In 1960 and 1961 one of the authors (Risso) investigated the social, cultural, genetic and other factors in the mental illnesses of 709 Italian patients in psychiatric clinics and mental hospitals in German-speaking Switzerland. These patients had rather unusual symptoms in that there was a mixture of normal ideas, which appeared to be derived from their cultural background, and psychotic or psychotic-like symptoms. It was therefore often difficult to allot these patients' illnesses to one of the usual diagnostic categories, so that it was not easy to decide if the patient had a schizophrenic episode, a schizophrenic reaction or a non-psychotic psychogenic reaction.

Idarubicin in combination with etoposide and cytarabine in adult untreated acute non lymphoblastic leukemia

Thirty-one unselected patients with untreated acute non lymphoblastic leukemia (ANLL) ranging in age from 15 to 76 years received two courses of a new high-dose induction regimen consisting of idarubicin, etoposide and cytarabine. Patients who entered complete remission (CR) were then allocated to post-remission intensification (PRI). Patients under 40 years of age with a HLA-compatible donor were given bone marrow transplantation (BMT); those without an HLA identical donor received either autologous BMT (ABMT) or no subsequent therapy. Twenty-five out of 31 patients (80.6%) achieved CR (93.3% in young and 68.7% in old patients) and 14 (56%) after the first cycle. Six patients (five out six greater than 40 years) died of cerebral hemorrhage and/or infection during the induction phase and four additional patients (three elderly) died on the PRI for the same cause without recurrent disease. Eleven out 25 patients are disease-free survivors 2-34 months (median 10 months) after achievement of CR. In conclusion, this intensive chemotherapy regimen is effective both in young and older patients but the post-remission intensification is too aggressive in elderly patients.

Bone marrow transplantation for severe aplastic anemia. A report of 9 cases

9 patients with severe aplastic anemia (SAA) were treated with bone marrow transplantation (BMT). 5 were conditioned with cyclophosphamide and received and HLA-identical graft (4 patients) or a mismatched graft (1 patient): 1 rejected the graft on day 30 and died on day 34 during conditioning for a second transplant; 1 died on day 15 with acute and severe graft versus host disease (GvHD) in the absence of haemopoietic engraftment; 3 are alive and complete chimeras at 1,069, 490 and 332 days after transplantation. GvHD developed in 4 patients and was treated successfully in 3 with high dose methylprednisolone and/or antilymphocytic globulin (ALG). 4 patients were conditioned with ALG and received bone marrow from a haploidentical sibling or parent: 1 patient was refractory; 3 patients showed evidence of hematologic reconstitution, but 2 of these required a second course of ALG. 3 patients in this group are alive between 60 and 490 days; 1 patient died on day 121 of HBSAg-negative acute hepatitis.

Hidden Structural Codes in Protein Intrinsic Disorder

Intrinsic disorder is a major structural category in biology, accounting for more than 30% of coding regions across the domains of life, yet consists of conformational ensembles in equilibrium, a major challenge in protein chemistry. Anciently evolved papillomavirus genomes constitute an unparalleled case for sequence to structure-function correlation in cases in which there are no folded structures. E7, the major transforming oncoprotein of human papillomaviruses, is a paradigmatic example among the intrinsically disordered proteins. Analysis of a large number of sequences of the same viral protein allowed for the identification of a handful of residues with absolute conservation, scattered along the sequence of its N-terminal intrinsically disordered domain, which intriguingly are mostly leucine residues. Mutation of these led to a pronounced increase in both α-helix and β-sheet structural content, reflected by drastic effects on equilibrium propensities and oligomerization kinetics, and uncovers the existence of local structural elements that oppose canonical folding. These folding relays suggest the existence of yet undefined hidden structural codes behind intrinsic disorder in this model protein. Thus, evolution pinpoints conformational hot spots that could have not been identified by direct experimental methods for analyzing or perturbing the equilibrium of an intrinsically disordered protein ensemble.