Analysis of association of FOXO3 gene with Trypanosoma cruzi infection and chronic Chagasic cardiomyopathy

FOXO3, a member of the Forkhead family of proteins, plays a role in controlling immune response. FOXO3 gene variant rs12212067 has been associated to differential severity of infectious diseases like malaria. In this study, we assessed whether this FOXO3 gene polymorphism is related to susceptibility to infection by Trypanosoma cruzi and/or chronic Chagasic cardiomyopathy. A total of 1171 individuals from a Colombian region endemic for Chagas disease, classified as seronegative (n = 595), seropositive asymptomatic (n = 175) and chronic Chagasic cardiomyopathy (n = 401) were genotyped for the FOXO3 rs12212067 using TaqMan allelic discrimination. Our results showed no statistically significantly differences between allelic and genotypic frequencies of rs12212067 in seronegative individuals compared with seropositive individuals. Similarly, we observed no evidence of association when asymptomatic individuals were compared with chronic Chagasic cardiomyopathy patients. Our data suggest that the FOXO3 genetic variant rs12212067 do not play an important role in Chagas disease.

Physiological and biochemical responses of Eichhornia crassipes exposed to Cr (III)

The effect of exposure of Eichhornia crassipes to Cr (III) was assessed by measuring changes in photosynthetic pigments, malondialdehyde, superoxide dismutase, glutathione reductase, catalase, and guaiacol peroxidase activities, as well as Cr concentration in tissues. Cr concentration in roots was significantly higher than in aerial parts and increased with Cr concentration in water. Photosynthetic pigments increased significantly, whereas the activities of antioxidant enzymes varied differently in plant tissues. Low Cr concentrations induced a rapid response of E. crassipes during short-term exposure, implying that the antioxidant system conferred redox homeostasis. Results showed that Cr (III) was more toxic at the two highest concentrations and long-term exposure, while it was not harmful but beneficial at the two lowest concentrations and short-term exposure. This work concludes that E. crassipes was able to grow under Cr (III) stress by protecting itself with an increase in the activity of its antioxidant system.

Interleukin 4, interleukin 4 receptor-α and interleukin 10 gene polymorphisms in Chagas disease

In this study, we investigated the association between single-nucleotide polymorphisms (SNPs) of the interleukin-4 (IL4), interleukin-4 receptor-α (IL4RA) and interleukin-10 (IL10) genes with the development of chagasic heart disease. This study included 260 patients from Colombia who were serologically positive for Trypanosoma cruzi antigens (cardiomyopathic, n=130; asymptomatic, n=130). Genotypes were determined by polymerase chain reaction (PCR)-restriction fragment length polymorphism or sequence-specific primer methods. We found statistically significant differences in the distribution of the IL4RA +148 AA (P=0·025, OR=1·89, CI=1·04-3·43) genotype when comparing asymptomatic and symptomatic patients. No statistically significant differences in the genotype and allele frequency of IL4 and IL10 gene polymorphisms between symptomatic and asymptomatic patients were observed. Our experimental evidence suggests that the IL4RA +148 AA genotype has a weak association with the development of chagasic cardiomyopathy in the population under study.

Lack of association between IL-6-174G/C gene polymorphism and Chagas disease

The aim of this study was to investigate the role of the IL-6-174G/C gene polymorphism in susceptibility/resistance to Trypanosoma cruzi infection in two independent cohorts from Colombia and Peru. We determined the IL-6-174G/C genotypes in a sample of 399 seronegative individuals and 317 serologically positive patients from Colombia and Peru. All individuals are from regions where T. cruzi infection is endemic. No statistically significant differences in the frequency of IL-6-174G/C gene polymorphism between chagasic patients and controls or between asymptomatic and individuals with cardiomyopathy were observed. Our results do not support an evidence for a major role contribution of this IL-6 gene polymorphism in the susceptibility to or clinical manifestations of Chagas disease in these studied cohorts.

[A case of mesenteric panniculitis]

Mesenteric panniculitis can be considered as an evolved state of a mesenteric disease, with a first phase of mesenteric lipodystrophy without inflammatory signs, followed by a second phase of panniculitis, ending in fibrosis, at which point it is denominated retractile mesentiritis, which principally affects males over the age of 50. Its aetiology is unknown, with a description made of different associated factors, and its clinical presentation is variable, depending on the stage of the disease. The image test indicated for its diagnosis is the TAC, while an histopathological study provides the definitive diagnosis. There are different medicines and therapeutic guidelines, although studies establishing the ideal treatment are lacking. We present the case of a patient diagnosed with mesenteric panniculitis who evolved favourably followed treatment with cyclophosphamide associated with corticoids.

[Merkel cell carcinoma. On one case]

We present the case of an 86 year old woman who was sent for consultation at General Surgery due to asymptomatic tumouration on the back face of the left thigh whose size had increased during the 2 previous months. Physical exploration revealed tumouration that was painless, excrescent, indurated, mobile and well delimited, with a diameter of 5 cm, a reddish colour and a rough surface. Tumoural extirpation was carried out with broad margins, with a hystopathological result of primary cutaneous neuro-endocrynal carcinoma or Merkel cell carcinoma. Computerised tomography was carried out, observing tumoural adenopathies in the para-aortic spaces, iliac chains and left femorals, as well as edema in the lower left extremity. The patient was sent to the Oncology service for treatment, without presenting a satisfactory evolution and with a progressive deterioration of her general state, dying within the first year after diagnosis.

Association study of PTPN22 C1858T polymorphism in Trypanosoma cruzi infection

In this study we investigated a possible role for the single nucleotide polymorphism C1858T of the PTPN22 (protein tyrosine phosphatase nonreceptor 22) gene in determining the susceptibility to Trypanosoma cruzi infection, as well as in development of chagasic heart disease. This study included 316 patients with Chagas' disease and 520 healthy individuals from Colombia and Peru. Genotyping of PTPN22 was performed by the real-time polymerase chain reaction technology, using the TaqMan 5' allelic discrimination assay. No statistically significant differences in the frequency of PTPN22 C1858T gene polymorphism between chagasic patients and controls or between asymptomatic and cardiomyopathic individuals were observed. Our findings suggest that the PTPN22 polymorphism analyzed does not play a major role in the development of Chagas' disease in the Colombian and Peruvian populations.

[Calcinosis cutis: on one case]

We present the case of a woman of 72 years with high blood pressure evaluated in Surgery Outpatient Unit for overinfected and recurring pretibial cutaneous ulcers. In the radiographies of the extremity, calcifications were observed in soft parts and the biopsy showed calcified subepidermic nodules. Because of these findings, she was sent to Internal Medicine Consultations to complete the study. In the anamnesis, traumatism in the zone was ruled out, and was there consumption of calcium or phosphorous rich medicines; the physical exploration was normal, except for the lesions described previously. A study was requested to rule out any underlying pathology that might justify the clinical picture, without a possible etiological pathological cause in evidence. Given that the cutaneous calcinosis of the patient was not secondary to titular lesions, nor was there evidence of metabolic alterations or medical procedures that might justify it, and no lesions at another level were found, the diagnosis was established of idiopathic localised cutaneous calcinosis. It was treated with diltiazem.

Characterization of reverse transcriptase activity of the L1Tc retroelement from Trypanosoma cruzi

The recombinant protein RTL1Tc, encoded by the non-LTR (long terminal repeat) retrotransposon L1Tc from Trypanosoma cruzi, has been shown to have reverse transcriptase (RT) activity using poly(rA)/oligo(dT) and poly(rC)/oligo(dG) homopolymers as template/primers. The optimal RT activity was detected at a concentration of 5 mM Mg2+, pH 8 and between 28 and 37% degrees C. Site-directed mutagenesis in the RT catalytic site proved that substitution of aspartic acid 313 for isoleucine (RT D313IL1Tc) practically abolishes the RT activity of the RTL1Tc protein. RT-polymerase chain reaction assays revealed that the RTL1Tc protein has the ability to use both homologous and heterologous RNA templates. Also, it is shown that the RTL1Tc protein is capable of synthesizing complementary DNA molecules by consecutive switching of the oligo molecule, which the protein uses as a template. This template switching may be involved in the retroelement integration process.

Nonsense-mediated mRNA decay in Saccharomyces cerevisiae

Cell survival depends on the precise and correct production of polypeptides. Eukaryotic cells have evolved conserved proofreading mechanisms to get rid of incomplete and potentially deleterious proteins. The nonsense-mediated mRNA decay (NMD) pathway is an example of a surveillance mechanism that monitors premature translation termination and promotes degradation of aberrant transcripts that code for nonfunctional or even harmful proteins. In this review we will describe our current knowledge of the NMD pathway, analyzing primarily the results obtained from the yeast Saccharomyces cerevisiae, but establishing functional comparisons with those obtained in higher eukaryotes. Based on these observations, we present two related working models to explain how this surveillance pathway recognizes and selectively degrades aberrant mRNAs.

The yeast hnRNP-like protein Hrp1/Nab4 marks a transcript for nonsense-mediated mRNA decay

The nonsense-mediated mRNA decay (NMD) pathway monitors premature translation termination and degrades aberrant mRNAs. In yeast, it has been proposed that a surveillance complex searches 3' of a nonsense codon for a downstream sequence element (DSE) associated with RNA-binding proteins. An interaction between the complex and the DSE-binding protein(s) triggers NMD. Here we describe the identification and characterization of the Hrp1/Nab4 protein as a DSE-binding factor that activates NMD. Mutations in HRP1 stabilize nonsense-containing transcripts without affecting the decay of wild-type mRNAs. Hrp1p binds specifically to a DSE-containing RNA and interacts with Upf1p, a component of the surveillance complex. A mutation in HRP1 that stabilizes nonsense-containing mRNAs abolishes its affinity for the DSE and fails to interact with Upf1p. We present a model describing how Hrp1p marks a transcript for rapid decay.

Should we kill the messenger? The role of the surveillance complex in translation termination and mRNA turnover

Eukaryotes have evolved conserved mechanisms to rid cells of faulty gene products that can interfere with cell function. mRNA surveillance is an example of a pathway that monitors the translation termination process and promotes degradation of transcripts harboring premature translation termination codons. Studies on the mechanism of mRNA surveillance in yeast and humans suggest a common mechanism where a "surveillance complex" monitors the translation process and determines whether translation termination has occurred at the correct position within the mRNA. A model will be presented that suggests that the surveillance complex assesses translation termination by monitoring the transition of an RNP as it is converted from a nuclear to a cytoplasmic form during the initial rounds of translation.

Mutations in the MOF2/SUI1 gene affect both translation and nonsense-mediated mRNA decay

Recent studies have demonstrated that cells have evolved elaborate mechanisms to rid themselves of aberrant proteins and transcripts. The nonsense-mediated mRNA decay pathway (NMD) is an example of a pathway that eliminates aberrant mRNAs. In yeast, a transcript is recognized as aberrant and is rapidly degraded if a specific sequence, called the DSE, is present 3' of a premature termination codon. Results presented here show that strains harboring the mof2-1, mof4-1, mof5-1, and mof8-1 alleles, previously demonstrated to increase the efficiency of programmed -1 ribosomal frameshifting, decrease the activity of the NMD pathway. The effect of the mof2-1 allele on NMD was characterized in more detail. Previous results demonstrated that the wild-type MOF2 gene is identical to the SUI1 gene. Studies on the mof2-1 allele of the SUI1 gene indicate that in addition to its role in recognition of the AUG codon during translation initiation and maintenance of the appropriate reading frame during translation elongation, the Mof2 protein plays a role in the NMD pathway. The Mof2p/Sui1 p is conserved throughout nature and the human homolog of the Mof2p/Sui1p functions in yeast cells to activate NMD. These results suggest that factors involved in NMD are general modulators that act in several aspects of translation and mRNA turnover.

Identifying the right stop: determining how the surveillance complex recognizes and degrades an aberrant mRNA

The nonsense-mediated mRNA decay (NMD) pathway functions by checking whether translation termination has occurred prematurely and subsequently degrading the aberrant mRNAs. In Saccharomyces cerevisiae, it has been proposed that a surveillance complex scans 3' of the premature termination codon and searches for the downstream element (DSE), whose recognition by the complex identifies the transcript as aberrant and promotes its rapid decay. The results presented here suggest that translation termination is important for assembly of the surveillance complex. Neither the activity of the initiation ternary complex after premature translation termination has occurred nor the elongation phase of translation are essential for the activity of the NMD pathway. Once assembled, the surveillance complex is active for searching and recognizing a DSE for approximately 200 nt 3' of the stop codon. We have also identified a stabilizer sequence (STE) in the GCN4 leader region that inactivates the NMD pathway. Inactivation of the NMD pathway, as a consequence of either the DSE being too far from a stop codon or the presence of the STE, can be circumvented by inserting sequences containing a new translation initiation/termination cycle immediately 5' of the DSE. Further, the results indicate that the STE functions in the context of the GCN4 transcript to inactivate the NMD pathway.

[Primitive neuroectodermal tumors: difficult tumors versus modern oncology]

INTRODUCTION

Primitive peripheral neuroectodermal tumours (PNET) are rare masses and form part of the group of round small cell tumours which include a wide range of highly aggressive neoplasias such as Ewing's sarcoma, neuroblastoma, lymphoma and rhabdomyosarcoma. PNET present the same cell line as the tumours presented by F. Askin in 1979, both located in the thoracic-pulmonary region.

MATERIAL AND METHODS

Of the last 26 thoracic neuroblastomas and 11 mediastinal-thoracic sarcomas treated at our centre, we observed 5 PNET in children with a mean age of 12 years (range: 9-14 years). These patients presented a thoracic mass infiltrating sternum, clavicle, supraspinal muscle or, in two cases, a left lateral or paravertebral intrathoracic mass. The time elapsed between clinical observation and diagnosis was 6 weeks. Diagnosis was established by chest X-Ray, CT, bone scintigraphy, immunocytochemistry and cytology. Aggressive local treatment associated with stage IV SIOP chemotherapy for rhabdomyosarcoma was applied in all cases to prevent metastasis.

RESULTS

Of the five PNET treated, one 16-year-old patient died (4 y 5 m post-diagnosis) from bone marrow infiltration which had evolved badly from the beginning. The remaining patients are disease-free. One patient who did not undergo surgery relapsed 1 year and the half after completing chemotherapy. He then underwent resection of the cranial portion of the sternum and substitution with iliac graft from the tissue bank.

CONCLUSION

PNET manifest clearly some of the characteristics of current paediatric oncology. These tumours are easily misdiagnosed and at present may be differentiated by new diagnostic methods (immunohistochemistry, cytogenetics, hybridomas, molecular genetics), with the aim of selecting the most adequate treatment and consequently improving the prognosis of these aggressive embryonary tumours.

Reverse transcriptase-like activity in Trypanosoma cruzi

The use of specific synthetic RNA homopolymers as templates and short oligonucleotides as primers has allowed evidence of the existence of a reverse transcriptase-like activity in Trypanosoma cruzi, to be revealed. The RNA:DNA products derived from this reaction are of approximately 110 nucleotides in length. The enzyme has greater affinity for poly(rA)/ oligo(dT) templates than for poly(rC)/oligo(dG) having a 20 mM Mg+2 ion requirement. The detected reverse transcriptase-like activity is not affected by aphidicolin and ddTTP but is inhibited by actinomycin D. novobiocin, rifamycin SV and AZT.

Current findings in the pathological evaluation of breast reduction specimens

A study of the histopathologic findings in the specimens of 100 consecutive cases of reduction mammoplasty was performed. The current classification of premalignant breast changes using the presence or absence of atypia in specimens with epithelial hyperplasia was employed. Of the group studied only 1% showed atypical ductal hyperplasia and no cases of lobular carcinoma in situ or ductal carcinoma in situ were found. Fifty percent of the specimens showed simply fibrosis of the stroma dominating the gross and microscopic picture. The other pathological findings in descending order of frequency were cysts (30%) epithelial hyperplasia without atypia (6%), adenosis (5%) and apocrine metaplasia (5%).