Revisiting the role of 3-nitrotyrosine residues in the formation of alpha-synuclein oligomers and fibrils.

Nitration of tyrosine residues in alpha-synuclein (a-syn) has been detected in different synucleinopathies, including Parkinson's disease. The potential role of 3-nitrotyrosine formation in a-syn, as an oxidative post-translational modification, is still elusive. In this work, we generated well-characterized tyrosine nitrated a-syn monomers and studied their capability to form oligomers and fibrils. We constructed tyrosine to phenylalanine mutants, containing a single tyrosine residue, a-syn mutant Y(125/133/136)F and Y(39/125/133)F) and assessed the impact in a-syn biophysical properties. Nitrated wild-type a-syn and the Y-F mutants, with one 3-nitrotyrosine residue in either the protein's N-terminal or C-terminal region, showed inhibition of fibril formation but retained the capacity of oligomer formation. The inhibition of a-syn fibrillation occurs even when an important amount of unmodified a-syn is still present. We characterized oligomers from both nitrated and non-nitrated forms of the wild-type protein and the mutant forms obtained. Our results indicate that the formation of 3-nitrotyrosine in a-syn could induce an off-pathway oligomer formation which may have an important impact in the development of synucleinopathies.

Overoxidation and Oligomerization of Trypanosoma cruzi Cytosolic and Mitochondrial Peroxiredoxins.

Peroxiredoxins (Prxs) have been shown to be important enzymes for trypanosomatids, counteracting oxidative stress and promoting cell infection and intracellular survival. In this work, we investigate the in vitro sensitivity to overoxidation and the overoxidation dynamics of Trypanosoma cruzi Prxs in parasites in culture and in the infection context. We showed that recombinant m-TXNPx, in contrast to what was observed for c-TXNPx, exists as low molecular mass forms in the overoxidized state. We observed that T. cruzi Prxs were overoxidized in epimastigotes treated with oxidants, and a significant proportion of the overoxidized forms were still present at least 24 h after treatment suggesting that these forms are not actively reversed. In in vitro infection experiments, we observed that Prxs are overoxidized in amastigotes residing in infected macrophages, demonstrating that inactivation of at least part of the Prxs by overoxidation occurs in a physiological context. We have shown that m-TXNPx has a redox-state-dependent chaperone activity. This function may be related to the increased thermotolerance observed in m-TXNPx-overexpressing parasites. This study suggests that despite the similarity between protozoan and mammalian Prxs, T. cruzi Prxs have different oligomerization dynamics and sensitivities to overoxidation, which may have implications for their function in the parasite life cycle and infection process.

Strikingly low prevalence of pituitary incidentalomas in a teaching hospital in Uruguay.

Background: Pituitary incidentalomas are an occurrence documented in 10.6% of post-mortem examinations, 4%-20% of computed tomography (CT) scans, and 10%-38% of magnetic resonance imaging (MRI) cases, primarily consisting of microincidentalomas (<1 cm in size). However, the prevalence of pituitary incidentalomas in Uruguay remains unexplored. This study aimed to ascertain the prevalence of pituitary incidentalomas at our hospital. Methods: In this investigation, we retrospectively identified patients who underwent brain CT and MRI at our hospital over a 1-year span due to conditions other than suspected or known pituitary disorders. The time frame covered was from 1 January to 31 December 2017. Our analysis encompassed all scans, and we conducted interviews with patients discovered to have pituitary incidentalomas. Furthermore, we conducted biochemical assessments in accordance with clinical and imaging traits. Results: During the study period, a total of 3,894 patients underwent imaging procedures. Of these, 1,146 patients underwent MRI scans, and 2,748 underwent CT scans. The mean age was 53.1 ± 19 years, with a relatively even distribution between genders (50.6% women). The majority of imaging requisitions originated from the emergency department (43%), followed by outpatient clinics (29%), and inpatient wards (28%). Common reasons for imaging requests included trauma (20.4%), headaches (11.3%), and stroke (10.9%). Among these cases, two pituitary incidentalomas were detected, resulting in a prevalence of 5 cases per 10,000 individuals annually (0.051%). Both of these cases were initially identified through CT scans, with subsequent MRI scans performed for further assessment. The final diagnoses were a vascular aneurysm and a sellar meningioma, with the latter patient also exhibiting secondary hypothyroidism. Notably, no instances of pituitary adenomas were encountered. Conclusions: The prevalence of pituitary incidentalomas within our hospital was notably low. Further research is necessary to more comprehensively investigate the occurrence of pituitary incidentalomas in our country.

Effect of the implementation of an enhanced recovery after surgery protocol (ERAS) in patients undergoing an elective cesarean section.

OBJECTIVES: To demonstrate that the application of an enhanced recovery after surgery (ERAS) protocol in elective cesarean sections is associated with reduced hospital stay without increasing maternal complications. MATERIAL AND METHODS: This retrospective, comparative study included patients who underwent an elective cesarean section. The patients were divided into groups: group 1, women who received elements of standardized care according to ERAS guidelines, and group 2, women who did not receive this care. RESULTS: The study included 295 patients, 139 in group 1 (ERAS) and 156 in group 2. The demographic characteristics were similar. Hospital stay and postoperative pain at 24 and 48 hours were lower in patients in group 1; these differences were statistically significant (p < 0.001). The overall complication rate, head pain, surgical wound infection, urinary retention, and readmission were similar in both groups. CONCLUSIONS: The application of an ERAS protocol can reduce hospital stay and postoperative pain without increasing the postoperative complication rate in patients who undergo an elective cesarean section. In developing countries, the application of this protocol could help in optimizing available health system resources.

Acute Sheehan's Syndrome Presenting with Hyponatremia Followed by a Spontaneous Pregnancy.

Background: Acute Sheehan's syndrome is rare, as well as hyponatremia as its initial manifestation. In addition, spontaneous pregnancy in patients after Sheehan's syndrome is unusual. To our knowledge, no cases of spontaneous pregnancy after acute Sheehan's syndrome have been reported. We describe a case of Sheehan's syndrome that presented with acute hyponatremia and a spontaneous pregnancy. Case: A 34-year-old female developed blood loss during delivery, which required a blood transfusion. On day seven postpartum, she presented with headaches, lethargy, and difficulty in breastfeeding. The workup showed hyponatremia (118 mEq/l), secondary hypothyroidism, and low prolactin levels. Magnetic resonance imaging showed pituitary necrosis. She was treated with NaCl, hydrocortisone (cortisol results were not available), and levothyroxine. Laboratory tests six weeks after discharge showed low IGF-1 and 8 AM cortisol and normal FT4, LH, FSH, and PRL levels. She was able to partially breastfeed until 4 months postpartum. Regular menstrual cycles started three months later. She became spontaneously pregnant one year later. Conclusion: Acute Sheehan's syndrome should be considered in the evaluation of postpartum patients with suggestive symptoms. Physicians should be aware that hyponatremia could be an initial manifestation of Sheehan's syndrome, which requires a high index of suspicion for diagnosis. Spontaneous pregnancy can occur after acute Sheehan's syndrome.

The Effects of Preimplantation Genetic Testing for Aneuploidy (PGT-A) on Patient-Important Outcomes in Embryo Transfer Cases: A Meta-Analysis.

Background: The aim of this study was to evaluate the effect of preimplantation genetic testing for aneuploidy (PGT-A) on patient-important reproductive outcomes after in vitro fertilization (IVF). Methods: Randomized and non-randomized studies have been sought in Ovid, MEDLINE, EMBASE, Web of Science, Scopus, and Cochrane Central Register of Controlled Trials since each database's inception through May 2021. Main keywords used for the search strategy included "Embryo transfer", "In vitro fertilization", "DNA sequencing", and "Comparative genome hybridization". Studies were screened independently and in duplicate. Results: Ten studies were finally analyzed, representing a total of 2630 embryo transfers. The pooled OR for live birth rates were 1.45 (95%CI 0.24-8.78, I2 96%) and 1.66 (95%PI 0.15-18.01, 95%CI 0.98-2.83, I2 81%) derived from the NRSIs and the RCTs, respectively, in which the miscarriage rate were 1.25 (95%CI 0.19-8.33, I2 70%) and 0.57 (95%PI 0.06-5.34, 95%CI 0.27-1.21, I2 53%), and clinical pregnancy rates were 3.08 (95%CI 2.22-4.29, I2 0%) and 1.43 (95%PI 0.38-5.42, 95%CI 0.96-2.13, I2 68%). Influence analyses showed a greater treatment effect when excluding studies without patients at advanced maternal age. Conclusion: There seems to be no significant difference in reproductive outcomes when using PGT-A in the general population; however, the procedure seems advantageous for patients at advanced maternal age. Nevertheless, this warrants caution when recommending the procedure to all couples seeking ART, as the current possible benefits may not justify the additional costs for all groups of patients.

Pituitary Society Delphi Survey: An international perspective on endocrine management of patients undergoing transsphenoidal surgery for pituitary adenomas.

PURPOSE: In adults and children, transsphenoidal surgery (TSS) represents the cornerstone of management for most large or functioning sellar lesions with the exception of prolactinomas. Endocrine evaluation and management are an essential part of perioperative care. However, the details of endocrine assessment and care are not universally agreed upon. METHODS: To build consensus on the endocrine evaluation and management of adults undergoing TSS, a Delphi process was used. Thirty-five statements were developed by the Pituitary Society's Education Committee. Fifty-five pituitary endocrinologists, all members of the Pituitary Society, were invited to participate in two Delphi rounds and rate their extent of agreement with statements pertaining to perioperative endocrine evaluation and management, using a Likert-type scale. Anonymized data on the proportion of panelists' agreeing with each item were summarized. A list of items that achieved consensus, based on predefined criteria, was tabulated. RESULTS: Strong consensus (≥ 80% of panelists rating their agreement as 6-7 on a scale from 1 to 7) was achieved for 68.6% (24/35) items. If less strict agreement criteria were applied (ratings 5-7 on the Likert-type scale), consensus was achieved for 88% (31/35) items. CONCLUSIONS: We achieved consensus on a large majority of items pertaining to perioperative endocrine evaluation and management using a Delphi process. This provides an international real-world clinical perspective from an expert group and facilitates a framework for future guideline development. Some of the items for which consensus was not reached, including the assessment of immediate postoperative remission in acromegaly or Cushing's disease, represent areas where further research is needed.

18F-fallypride and 11C-methionine positron emission tomography/computed tomography for the study of prolactinomas and nonfunctioning pituitary adenomas: A case series.

Some studies have assessed the expression of dopaminergic dopamine 2 (D2)/3 receptors in prolactinomas and nonfunctioning pituitary adenomas (NFPA) by positron emission tomography/computed tomography (PET/CT) with 11C-raclopride, proving that this modality can be useful to predict the response to treatment with dopamine agonists. However, the use of 11C-labeled radiotracers is limited, as it requires a cyclotron in the PET center. 18F-fallypride is a radiotracer that has proven useful in assessing the expression of D2/3 receptors. As it is labeled with 18F, it can be produced and transported to distant PET centers. There are no studies on the usefulness of 18F-fallypride for the evaluation of patients with prolactinomas and NFPA. The aim of this study was to describe the first case series of patients with prolactinomas and NFPA studied with 18F-fallypride and 11C-methionine PET/CT to reveal D2/3 expression and amino acid (AA) metabolism. 18F-fallypride and 11C-methionine uptake were assessed in a case series of six patients, five with prolactinomas and one with a NFPA, and compared with clinical presentation and follow-up at 6-18 months. All patients presented with macroadenomas, with a wide range of AA metabolism, as revealed by 11C-methionine PET/CT. 18F-fallypride PET/CT identified low to moderate/high D2/3 expression in the tumors. The patient that presented low expression of D2/3 in the tumor and high AA metabolism showed a poor response to DA therapy. 18F-fallypride was able to reveal D2/3 receptor expression in prolactinomas and NFPA, with the advantage of been a more accessible radiotracer in comparison with previous 11C labeled analogs.

The cytosolic tryparedoxin peroxidase from Trypanosoma cruzi induces a pro-inflammatory Th1 immune response in a peroxidatic cysteine-dependent manner.

Trypanosoma cruzi cytosolic tryparedoxin peroxidase (c-TXNPx) is a 2-Cys peroxiredoxin (Prx) with an important role in detoxifying host cell oxidative molecules during parasite infection. c-TXNPx is a virulence factor, as its overexpression enhances parasite infectivity and resistance to exogenous oxidation. As Prxs from other organisms possess immunomodulatory properties, we studied the effects of c-TXNPx in the immune response and analysed whether the presence of the peroxidatic cysteine is necessary to mediate these properties. To this end, we used a recombinant c-TXNPx and a mutant version (c-TXNPxC52S) lacking the peroxidatic cysteine. We first analysed the oligomerization profile, oxidation state and peroxidase activity of both proteins by gel filtration, Western blot and enzymatic assay, respectively. To investigate their immunological properties, we analysed the phenotype and functional activity of macrophage and dendritic cells and the T-cell response by flow cytometry after injection into mice. Our results show that c-TXNPx, but not c-TXNPxC52S, induces the recruitment of IL-12/23p40-producing innate antigen-presenting cells and promotes a strong specific Th1 immune response. Finally, we studied the cellular and humoral immune response developed in the context of parasite natural infection and found that only wild-type c-TXNPx induces proliferation and high levels of IFN-γ secretion in PBMC from chronic patients without demonstrable cardiac manifestations. In conclusion, we demonstrate that c-TXNPx possesses pro-inflammatory properties that depend on the presence of peroxidatic cysteine that is essential for peroxidase activity and quaternary structure of the protein and could contribute to rational design of immune-based strategies against Chagas disease.

Trypanothione Metabolism as Drug Target for Trypanosomatids.

Chagas Disease, African sleeping sickness, and leishmaniasis are neglected diseases caused by pathogenic trypanosomatid parasites, which have a considerable impact on morbidity and mortality in poor countries. The available drugs used as treatment have high toxicity, limited access, and can cause parasite drug resistance. Long-term treatments, added to their high toxicity, result in patients that give up therapy. Trypanosomatids presents a unique trypanothione based redox system, which is responsible for maintaining the redox balance. Therefore, inhibition of these essential and exclusive parasite's metabolic pathways, absent from the mammalian host, could lead to the development of more efficient and safe drugs. The system contains different redox cascades, where trypanothione and tryparedoxins play together a central role in transferring reduced power to different enzymes, such as 2-Cys peroxiredoxins, non-selenium glutathione peroxidases, ascorbate peroxidases, glutaredoxins and methionine sulfoxide reductases, through NADPH as a source of electrons. There is sufficient evidence that this complex system is essential for parasite survival and infection. In this review, we explore what is known in terms of essentiality, kinetic and structural data, and the development of inhibitors of enzymes from this trypanothione-based redox system. The recent advances and limitations in the development of lead inhibitory compounds targeting these enzymes have been discussed. The combination of molecular biology, bioinformatics, genomics, and structural biology is fundamental since the knowledge of unique features of the trypanothione-dependent system will provide tools for rational drug design in order to develop better treatments for these diseases.

Cateterismo de senos petrosos en el diagnóstico etiológico de síndrome de Cushing: primera experiencia en Uruguay / Petrosal sinus sampling for etiological diagnosis of Cushing's syndrome: first experience in Uruguay / Cateterismo dos seios petrosos no diagnóstico etiológico da síndrome de Cushing: primeira experiência no Uruguai

Resumen: Identificar la causa de un síndrome de Cushing dependiente de adrenocorticotropina (ACTH) es esencial para realizar un tratamiento correcto. La hipersecreción de ACTH es debida en su mayoría a un tumor hipofisario (enfermedad de Cushing) o, en un 10%-20%, a tumores con producción ectópica de esta hormona. Los test no invasivos tienen baja sensibilidad y especificidad para diferenciar estas dos etiologías. El patrón oro lo constituye el cateterismo bilateral de los senos petrosos inferiores (CSP). Mediante el CSP se demuestra la hipersecreción de ACTH a nivel hipofisario al documentar un gradiente de ACTH central a periférico en el drenaje del tumor. Se recomienda realizarlo en todo síndrome de Cushing ACTH dependiente, aunque suele reservarse para pacientes con diagnóstico de hipercortisolismo y hallazgos negativos o equívocos en la resonancia nuclear magnética (RNM) de la región selar. Presentamos el primer caso en Uruguay en que se utilizó el CSP como método diagnóstico, una mujer de 55 años que presentó un hipercortisolismo ACTH-dependiente con una imagen adenohipofisaria <6 mm. El gradiente petroso-periférico confirmó el diagnóstico de enfermedad de Cushing y no hubo complicaciones durante el procedimiento. Posteriormente se realizó la resección del adenoma mediante cirugía transesfenoidal, con buena evolución y confirmación inmunohistoquímica del tumor.

Summary: Identifying the cause of adrenocorticotropin (ACTH)-dependent Cushing's syndrome is key to define the appropriate treatment. Hypersecretion of the adrenocorticotropic hormone (ACTH) is mainly caused by a pituitary tumor (Cushing's syndrome) or, in 10% to 20% of cases, by tumors with ectopic production of this hormone. Differentiation between these two etiologies may not be easy due to the low sensitivity and specificity of non- invasive tests. Bilateral sampling of the lower petrosal sinus is the gold standard to differentiate between a pituitary and an ectopic origin, showing the pituitary ACHT hypersecretion and recording the central-to-peripheral ACTH gradient in the tumor's drainage. Despite it being highly recommended for all cases of ACTH-dependent Cushing's syndrome, it is reserved for patients with a diagnosis of hypercortisolism and negative or misleading findings in the MRI of the sellar region. The study presents the first case of petrosal sinus sampling for diagnostic purposes in Uruguay, in a 55-year-old woman with ACHT-dependent hypercortisolism showing an adenohypophysis image < 6 mm. The petrosal-peripheral gradient confirmed the diagnosis of Cushing's syndrome and no complications arose during the procedure. Afterwards a transsphenoidal surgery was performed for resection of the adenoma. Evolution was good and immunochemistry confirmed the tumor's etiology.

Resumo: Identificar a causa da síndrome de Cushing dependente de adrenocorticotropina (ACTH) é essencial para o tratamento adequado. A hipersecreção de ACTH se deve principalmente a um tumor hipofisário (doença de Cushing) ou, em 10%-20%, a tumores com produção ectópica desse hormônio. Os testes não invasivos apresentam baixa sensibilidade e especificidade para diferenciar essas duas etiologias. O padrão ouro é o cateterismo bilateral dos seios petrosos inferiores (CEP). O CSP demonstra hipersecreção de ACTH no nível da hipófise, documentando um gradiente de ACTH central a periférico na drenagem do tumor. É recomendado nos casos de síndrome de Cushing dependente de ACTH, embora seja geralmente reservado para pacientes com diagnóstico de hipercortisolismo e achados negativos ou duvidosos na ressonância magnética (RNM) da região selar. Apresentamos o primeiro caso no Uruguai em que o CSP foi usado como método diagnóstico, uma mulher de 55 anos que apresentava hipercortisolismo ACTH dependente com imagem da hipófise anterior <6 mm. O gradiente petroso-periférico confirmou o diagnóstico de doença de Cushing e não houve complicações durante o procedimento. A seguir, o adenoma foi ressecado por cirurgia transesfenoidal, com boa evolução e confirmação imunohistoquímica do tumor.

Excessive Maternal Weight and Diabetes Are Risk Factors for Macrosomia: A Cross-Sectional Study of 42,663 Pregnancies in Uruguay.

Objective: To evaluate the risk of macrosomia in newborns from women with gestational diabetes, pregestational diabetes, overweight, and obesity in Uruguay in 2012, as well as its association with prolonged pregnancy, maternal age, multiparity, and excessive gestational weight gain (EGWG). Methods: We performed a cross-sectional study of 42,663 pregnant women. The risk of macrosomia was studied using logistic regression. Results: Mean maternal age was 26.7 ± 6.8 years. Pregestational overweight and obesity was present in 20.9% and 10.7% of women, respectively. There were 28.1% and 19.8% of women overweight and obese at the end of the pregnancy, respectively. Furthermore, 0.5% had pregestational diabetes and 8.5% were multiparous. Twenty two percent developed gestational diabetes and 44.9% had EGWG. The prevalence of macrosomia was 7.9%, significantly more prevalent in males (10.0% vs. 5.5%, p<0.005). Univariate analysis showed that obesity and overweight pre-pregnancy, obesity and overweight at the end of pregnancy, EGWG, pregestational diabetes, gestational diabetes, multiparity, prolonged pregnancy, and male newborn were strongly associated with macrosomia (p<0.0001). Maternal age >35 years did not increase the risk of macrosomia. After multiple logistic regression macrosomia was more likely in pre-gestational obese women (OR 1.24; CI 1.07-1.44), overweight women at the end of pregnancy (OR 1.66; CI 1.46-1.87), obese women at the end of pregnancy (OR 2.21; CI 1.90-2.58), women with EGWG (OR 1.78; CI 1.59-1.98), pregestational diabetes (OR 1.75; CI 1.15-2.69), gestational diabetes (OR 1.39; CI 1.25-1.53), prolonged pregnancy (OR 2.67; CI 2.28-3.12), multiparity (OR 1.24; CI 1.04-1.48), and male newborn (OR 1.89; CI 1.72-2.08). Conclusion: Maternal overweight, obesity, EGWG, and gestational diabetes are prevalent in Uruguay, increasing the risk of macrosomia. Efforts to implement strategies to decrease the prevalence of overweight and obesity among women of reproductive age are essential to improve maternal and neonatal outcomes.

Pituitary society guidance: pituitary disease management and patient care recommendations during the COVID-19 pandemic-an international perspective.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the viral strain that has caused the coronavirus disease 2019 (COVID-19) pandemic, has presented healthcare systems around the world with an unprecedented challenge. In locations with significant rates of viral transmission, social distancing measures and enforced 'lockdowns' are the new 'norm' as governments try to prevent healthcare services from being overwhelmed. However, with these measures have come important challenges for the delivery of existing services for other diseases and conditions. The clinical care of patients with pituitary disorders typically involves a multidisciplinary team, working in concert to deliver timely, often complex, disease investigation and management, including pituitary surgery. COVID-19 has brought about major disruption to such services, limiting access to care and opportunities for testing (both laboratory and radiological), and dramatically reducing the ability to safely undertake transsphenoidal surgery. In the absence of clinical trials to guide management of patients with pituitary disease during the COVID-19 pandemic, herein the Professional Education Committee of the Pituitary Society proposes guidance for continued safe management and care of this population.

Clinical Pregnancy After Elimination of Embryo Fragments Before Fresh Cleavage-stage Embryo Transfer.

Objective: To determine if the elimination of fragments in cleavage-stage embryos, before fresh transfer, improves pregnancy rates in in vitro fertilization cycles. Materials and methods: This is a Prospective observational case-control study carried out at a University Reproductive Center. We included Twenty-six infertile patients divided into two groups. Group one: 13 patients with embryos classified as grade B and C (embryos with fragments) according to the Hill classification, and Group two: 13 patients with grade A embryos (embryos with no fragments). Embryo Defragmentation was performed in embryos of group one 65 to 68 hours after conventional fertilization. Fresh embryo transfer was made after two hours post fragments removal. Reproductive results were evaluated and compared between both groups. Results: The total number of clinical pregnancies was nine. In group one there were 5 (38.5 %); in group two, there were 4 (30.8%). The difference was not statistically significant (p = 0.68). Two abortions were reported in the study, both in group one; were fragment elimination was performed. This represents an abortion rate of 40% in patients who got pregnant in this group. These patients had twice the probability of suffering an abortion (OR 2.1; 95% CI 1.4-3.37). Ongoing pregnancies were similar in both groups. Conclusion: Removal of fragments in freshly transferred day three embryos could be an alternative to increase clinical pregnancy and ongoing pregnancy rates in patients who have only poor-quality embryos. Despite the relationship with a higher abortion rate, this strategy could represent a real alternative for this type of patient.

Oligomerization dynamics and functionality of Trypanosoma cruzi cytosolic tryparedoxin peroxidase as peroxidase and molecular chaperone.

BACKGROUND: Trypanosoma cruzi cytosolic tryparedoxin peroxidase (c-TXNPx) is a 2-Cys peroxiredoxin that plays an important role in coping with host cell oxidative response during the infection process, for which it has been described as a virulence factor. METHODS: Four residues corresponding to c-TXNPx catalytic and solvent-exposed cysteines were individually mutated to serine by site-specific mutagenesis. Susceptibility to redox treatments and oligomeric dynamics were investigated by western-blot and gel filtration chromatography. Chaperone and peroxidase activities were determined. RESULTS: In this study we demonstrated that c-TXNPx exists as different oligomeric forms, from decameric to high molecular mass aggregates. Moreover, c-TXNPx functions as a dual-function protein acting both as a peroxidase and as a molecular chaperone. Its chaperone function was shown to be independent of the presence of catalytic cysteines, even in the reduced and decameric forms, although it is enhanced when the protein is overoxidized leading to the formation of high molecular mass aggregates. CONCLUSIONS: c-TXNPx has chaperone activity which does not depend on the redox state. c-TXNPx does not undergo the dimer-decamer transition in the oxidized state described for other peroxiredoxins. Overoxidized c-TXNPx exists as different oligomeric forms from decamer to high molecular mass aggregates which are in a very slow dynamic equilibrium. The non-catalytic C57 residue may have a role in the maintenance of the decameric form, but seems not to have an alternative CP and CR role. GENERAL SIGNIFICANCE: This study provides novel insights into some key aspects of the oligomerization dynamics and function of c-TXNPx.

Cytosolic Fe-superoxide dismutase safeguards Trypanosoma cruzi from macrophage-derived superoxide radical.

Trypanosoma cruzi, the causative agent of Chagas disease (CD), contains exclusively Fe-dependent superoxide dismutases (Fe-SODs). During T. cruzi invasion to macrophages, superoxide radical (O2•-) is produced at the phagosomal compartment toward the internalized parasite via NOX-2 (gp91-phox) activation. In this work, T. cruzi cytosolic Fe-SODB overexpressers (pRIBOTEX-Fe-SODB) exhibited higher resistance to macrophage-dependent killing and enhanced intracellular proliferation compared with wild-type (WT) parasites. The higher infectivity of Fe-SODB overexpressers compared with WT parasites was lost in gp91-phox-/- macrophages, underscoring the role of O2•- in parasite killing. Herein, we studied the entrance of O2•- and its protonated form, perhydroxyl radical [(HO2•); pKa = 4.8], to T. cruzi at the phagosome compartment. At the acidic pH values of the phagosome lumen (pH 5.3 ± 0.1), high steady-state concentrations of O2•- and HO2• were estimated (∼28 and 8 µM, respectively). Phagosomal acidification was crucial for O2•- permeation, because inhibition of the macrophage H+-ATPase proton pump significantly decreased O2•- detection in the internalized parasite. Importantly, O2•- detection, aconitase inactivation, and peroxynitrite generation were lower in Fe-SODB than in WT parasites exposed to external fluxes of O2•- or during macrophage infections. Other mechanisms of O2•- entrance participate at neutral pH values, because the anion channel inhibitor 5-nitro-2-(3-phenylpropylamino) benzoic acid decreased O2•- detection. Finally, parasitemia and tissue parasite burden in mice were higher in Fe-SODB-overexpressing parasites, supporting the role of the cytosolic O2•--catabolizing enzyme as a virulence factor for CD.

Factitious Cushing's Syndrome: A Diagnosis to Consider When Evaluating Hypercortisolism.

Factitious Cushing's syndrome is exceptionally rare. The diagnosis is challenging due to the interference of exogenous corticosteroids with cortisol immunoassays. We present a case of a 26 year old female that presented with clinical and biochemical features of Cushing's syndrome. She denied any exogenous corticosteroid use. She had a suppressed ACTH level with normal adrenal glands on CT scans. There was a paradoxical increase of cortisol with a 100% rise in 24 h urinary free cortisol (UFC) during the Liddle's test suggestive of primary pigmented nodular adrenocortical disease (PPNAD). However, basal UFC levels were within normal values, interpreted as an intermittent variation of cortisol secretion maybe due to cyclic Cushing's. At this point a synthetic glucocorticoid serum screening was ordered, which was denied by the administrators because the test was not available in our hospital. A positron emission tomography (PET)-CT using 18 F-Flurodeoxyglucose did not show any uptake in the adrenal glands. With the diagnosis of probable primary pigmented nodular adrenocortical disease a unilateral right adrenelectomy was performed. Histopathological examination revealed normal adrenal gland. A synthetic glucocorticoid serum screen by liquid chromatography-tandem mass spectrometry (LC-MS/MS) sent to Mayo Clinic lab revealed high levels of serum prednisone and prednisolone. In conclusion, factitious Cushing's syndrome is an important diagnosis to consider in patients being evaluated for hypercortisolism. Discordant hormonal test results as well as normal findings on adrenal glands on CT scan should raise suspicion of this entity, and prompt measurement of synthetic corticosteroids using LC-MS/MS.

Evaluation of the immune response against Trypanosoma cruzi cytosolic tryparedoxin peroxidase in human natural infection.

Trypanosoma cruzi, the aetiological agent of Chagas disease, has a highly efficient detoxification system to deal with the oxidative burst imposed by its host. One of the antioxidant enzymes involved is the cytosolic tryparedoxin peroxidase (c-TXNPx), which catalyses the reduction to hydrogen peroxide, small-chain organic hydroperoxides and peroxynitrite. This enzyme is present in all parasite stages, and its overexpression renders parasites more resistant to the oxidative defences of macrophages, favouring parasite survival. This work addressed the study of the specific humoral and cellular immune response triggered by c-TXNPx in human natural infection. Thus, sera and peripheral blood mononuclear cells (PBMC) were collected from chronically infected asymptomatic and cardiac patients, and non-infected individuals. Results showed that levels of IgG antibodies against c-TXNPx were low in sera from individuals across all groups. B-cell epitope prediction limited immunogenicity to a few, small regions on the c-TXNPx sequence. At a cellular level, PBMC from asymptomatic and cardiac patients proliferated and secreted interferon-γ after c-TXNPx stimulation, compared with mock control. However, only proliferation was higher in asymptomatic patients compared with cardiac and non-infected individuals. Furthermore, asymptomatic patients showed an enhanced frequency of CD19+ CD69+ cells upon exposure to c-TXNPx. Overall, our results show that c-TXNPx fails to induce a strong immune response in natural infection, being measurable only in those patients without any clinical symptoms. The low impact of c-TXNPx in the human immune response could be strategic for parasite survival, as it keeps this crucial antioxidant enzyme activity safe from the mechanisms of adaptive immune response.