Metabarcoding reveals that a non-nutritive sweetener and sucrose yield similar gut microbiota patterns in Wistar rats.

The effects of non-nutritive sweeteners (NNS) on the gut microbiota are an area of increasing research interest due to their potential influence on weight gain, insulin resistance, and inflammation. Studies have shown that mice and rats fed saccharin develop weight gain and metabolic alterations, possibly related to changes in gut microbiota. Here, we hypothesized that chronic exposure to a commercial NNS would change the gut microbiota composition in Wistar rats when compared to sucrose exposure. To test this hypothesis, Wistar rats were fed either NNS- or sucrose-supplemented yogurt for 17 weeks alongside standard chow (ad libitum). The gut microbiome was assessed by 16S rDNA deep sequencing. Assembly and quantification were conducted using the Brazilian Microbiome Project pipeline for Ion Torrent data with modifications. Statistical analyses were performed in the R software environment. We found that chronic feeding of a commercial NNS-sweetened yogurt to Wistar rats, within the recommended dose range, did not significantly modify gut microbiota composition in comparison to sucrose-sweetened yogurt. Our findings do not support the hypothesis that moderate exposure to NNS is associated with changes in gut microbiota pattern compared to sucrose, at least in this experimental model.

Apoptotic activity and Treg cells in tissue lesions of patients with leprosy.

In order to understand the apoptotic response and the participation of Treg cells in the spectral clinical evolution of leprosy, this study evaluated the immunohistochemical expression of caspase-3 and FoxP3 in skin lesions of leprosy patients with the polar forms of the disease. Forty-nine patients with a confirmed diagnosis of the disease were selected, including 27 with the TT form and 22 with the LL form. Quantitative analysis of caspase-3 immunostaining showed a higher expression of this mediator in the LL form (3.409 ± 0.6517 cells/mm(2); p = 0.0001). Immunostaining for the transcription factor FoxP3 was higher in the LL form (3.891 ± 0.9294 cells/mm(2); p = 0.0001). A moderate correlation between the two markers was observed in the TT form (r = 0.5214; p = 0.005). It can be concluded that Treg cells and apoptosis play an effective role for the host defense response, inducing mechanisms involved in the activation of cascades that interfere with the control of the immune response and cell homeostasis.

Relationship between growth factors and its implication in the pathogenesis of leprosy.

Leprosy is a chronic infectious disease caused by Mycobacterium leprae which affects the skin and peripheral nervous system. The immune response of the host determines the clinical course of the disease. The tuberculoid form is the result of high cell-mediated immunity characterized by a Th1 response, whereas the lepromatous form is characterized by low cell-mediated immunity and a Th2 humoral response. The neural damage established produces marked changes in the expression of growth factors such as nerve growth factor (NGF) and its receptors (NGF-R). The expression of NGF, associated with the expression of Th1 and Th2 cytokines, might be involved in the tissue damage caused by the bacillus. Therefore, the objective of this study was to correlate the immunoexpression patterns of NGF and NGF-R in the different clinical forms of leprosy, and to associate the findings with the in situ expression of TGF-ß and clinical classification of the disease. TGF-ß, NGF and NGF-R immunoexpression was analyzed by immunohistochemistry in paraffin-embedded material. Most patients were males with a mean age of 40.7 years. TGF-ß levels were significantly higher in the lepromatous forms. No significant difference in the immunoexpression of NGF or NGF-R was observed between the clinical forms, but expression tended to be higher at the lepromatous pole. There was a significant positive correlation between NGF and NGF-R in the different clinical forms of leprosy. A significant positive correlation was observed between NGF, NGF-R and TGF-ß. It can be concluded that, even existing evidence on the role of these molecules in the clinical spectrum of leprosy.

Severe Mitral Valve Regurgitation in Infective Endocarditis: A Case Report.

We present a case report of a patient with infective endocarditis. He came to the emergency room with respiratory failure due to severe pneumonia and pulmonary edema. On 2D transesophageal echocardiography, vegetations were seen in both mitral and aortic valves, with mitral valve perforation and severe regurgitation. His clinical presentation and severity of the disease made him suitable for urgent valve repair. He was submitted to mitral valvuloplasty with closure of the valve perforation and insertion of a bioprosthetic aortic valve. Despite significant clinical improvement, a post-surgical complication was noted with new-onset lung injury after cardiopulmonary bypass. This is an interesting case of a patient with suspected retrograde valve involvement, affecting the aortic valve, the mitral-aortic intervalvular fibrosa, and the mitral valve, ending with mitral valve abscess with leaflet perforation and valvular regurgitation.

P-glycoprotein efflux pump plays an important role in Trypanosoma cruzi drug resistance.

Drug resistance in protozoan parasites has been associated with the P-glycoprotein (Pgp), an energy-dependent efflux pump that transports substances across the membrane. Interestingly, the genes TcPGP1 and TcPGP2 have been described in Trypanosoma cruzi, although the function of these genes has not been fully elucidated. The main goal of this work was to investigate Pgp efflux pump activity and expression in T. cruzi lines submitted to in vitro induced resistance to the compounds 4-N-(2-methoxy styryl)-thiosemicarbazone (2-Meotio) and benznidazole (Bz) and to verify the stability of the resistant phenotypes during the parasite life cycle. We observed that the EC50 values for the treatment of epimastigotes with 2-Meotio or Bz were increased at least 4.7-fold in resistant lines, and this phenotype was maintained in metacyclic trypomastigotes, cell-derived trypomastigotes, and intracellular amastigotes. However, in epimastigotes, 2-Meotio resistance is reversible, but Bz resistance is irreversible. When compared with the parental line, the resistant lines exhibited higher Pgp efflux activity, reversion of the resistant phenotypes in the presence of Pgp inhibitors, cross-resistance with Pgp modulators, higher basal Pgp ATPase activity, and overexpression of the genes TcPGP1 and TcPGP2. In conclusion, the resistance induced in T. cruzi by the compounds 2-Meotio and Bz is maintained during the entire parasite life cycle. Furthermore, our data suggest the participation of the Pgp efflux pump in T. cruzi drug resistance.

Physical activity based on dance movements as complementary therapy for Parkinson's disease: Effects on movement, executive functions, depressive symptoms, and quality of life.

BACKGROUND: Parkinson's disease (PD) is a progressive, neurodegenerative disease with motor symptoms that are well understood, but non-motor symptoms may be present and appear at different temporal stages of the disease. Physical activity based on dance movements is emerging as a complementary therapeutic approach to a range of PD symptoms as a multidimensional activity that requires rhythmic synchronization and more neuromuscular functions. OBJECTIVE: To evaluate the effects of physical activity based on dance movements on the movement, executive functions, depressive symptoms, quality of life, and severity of PD in individuals diagnosed with PD. METHODS: 13 individuals with PD (Hoehn & Yahr I-III, MDS-UPDRS 67.62 ± 20.83), underwent physical activity based on dance movements (2x week for 6 months). Participants were assessed at baseline and after 6 months on movement (POMA, TUG and MDS-UPDRS Part III), executive function (FAB), depressive symptoms (MADRS), quality of life (PDQ-39), and severity of PD (MDS-UPDRS TOTAL). Student's t-test was used to compare pre and post-intervention results. RESULTS: We observed a significant improvement in the movement (balance and gait) by the POMA test, p = 0.0207, executive function by the FAB test, p = 0.0074, abstract reasoning and inhibitory control by the FAB, Conceptualization test, p = 0.0062, and Inhibitory Control, p = 0.0064, depressive symptoms assessed by the MADRS test significantly reduced, p = 0.0214, and the quality of life by the PDQ-39 had a significant increase after the intervention, p = 0.0006, showed significant improvements between the pre-and post-intervention periods of physical activity based on dance movements. CONCLUSION: Physical activity based on dance movements contributed to significant improvements in movement (balance and gait), executive functions, especially in cognitive flexibility and inhibitory control, and the quality of life too. Sensorimotor integration, most cognitive processing and social skills may have contributed to the results. TRIAL REGISTRATION: The study was registered in the Brazilian registry of clinical trials: RBR-3bhbrb5.

Investigation of trypanothione reductase inhibitory activity by 1,3,4-thiadiazolium-2-aminide derivatives and molecular docking studies.

The biological activities of a series of mesoionic 1,3,4-thiadiazolium-2-aminide derivatives have been studied. The most active compounds (MI-HH; MI-3-OCH(3); MI-4-OCH(3) and MI-4-NO(2)) were evaluated to determine their effect on trypanothione reductase (TryR) activity in Leishmania sp. and Trypanosoma cruzi. Among the assayed compounds, only MI-4-NO(2) showed enzyme inhibition effect on extracts from different cultures of parasites, which was confirmed using the recombinant enzyme from T. cruzi (TcTryR) and Leishmania infantum (LiTryR). The enzyme kinetics determined with LiTryR demonstrated a non-competitive inhibition profile of MI-4-NO(2). A molecular docking study showed that the mesoionic compounds could effectively dock into the substrate binding site together with the substrate molecule. The mesoionic compounds were also effective ligands of the NADPH and FAD binding sites and the NADPH binding site was predicted as the best of all three binding sites. Based on the theoretical results, an explanation at the molecular level is proposed for the MI-4-NO(2) enzyme inhibition effect. Given TryR as a molecular target, it is important to continue the study of mesoionic compounds as part of a drug discovery campaign against Leishmaniasis or Chagas' disease.

Occupational Therapy for People Living With Human T-Lymphotropic Virus 1: Importance and Effectiveness of an Intervention Plan at the Level of Prevention and Rehabilitation.

Introduction: Human T-lymphotropic virus 1 (HTLV-1)-associated myelopathy (HAM) restricts activities of daily living (ADLs), affecting health and quality of life. Occupational therapy is used to promote independence during ADL in people living with HTLV (PLHTLV). Objective: To quantify the clinical aspects, levels of functionality, performance in ADLs and occupational roles of PLHTLV and propose an occupational therapeutic intervention. Method: A cross-sectional, descriptive, observational study was designed with 40 PLHTLV monitored at two referral laboratories of the Federal University of Pará. The Evandro Chagas Research Institute Neurological Disability Scale (EIPEC-2), the Barthel Index and the Occupational Roles Identification List were applied. The G test and Fisher's exact test (to identify associations between qualitative variables), the Mann-Whitney test (to identify associations between quantitative variables) and Pearson correlation analysis (to identify associations between the total Barthel Index and EIPEC-2 scores) were performed with Microsoft Excel and BioEstat 5.0, and the significance level was set at p ≤ 0.05. Results: Motor aspects, the presence of spasticity, sensory aspects, and pain in the lumbar region and lower limbs were significantly (p = 0.0002) higher among symptomatic individuals, who also had more difficulties urinating, traveling up and down stairs and transferring from a chair to a bed. Being a worker, performing housework and socializing (with friends or family members) were the most affected activities among HAM patients. Conclusion: The impact of HAM on PLHTLV should include an intervention plan with occupational therapists in rehabilitation programs to create an important third-level prevention initiative, which may help achieve short-, medium-, and long-term goals. Asymptomatic PLHTLV should also be able to prevent future ADL impairment.

Providing a Nursing Care Plan as a Requirement for Secondary Prevention for People Living With HTLV-1.

Introduction: The absence of nursing care plans aimed at people living with HTLV-1 (PLHTLV) led us to develop and test a proposed nursing care plan based on the evaluation of 55 PLHTLV to outline interventions according to the clinical stage. Methods: After interviews with symptomatic patients, nursing diagnoses were made using the NANDA International Nursing Diagnoses (The International Nursing Knowledge Association). Subsequently, interventions were selected through the Classification of Nursing Interventions (NIC), and expected results were selected through the Classification of Nursing Outcomes (NOC). Results: The actual diagnoses included (ii) chronic pain, (iii) impaired urinary elimination, and (iv) sexual dysfunction; the health promotion diagnosis was (i) risk-prone health behavior; and the risk diagnoses were (i) risk of feeling powerless and (ii) risk of falls in adults. Nursing care must prevent the lack of adherence to monitoring, establish goals and promote family involvement. A safe home environment requires intervention for fall prevention. Full support in understanding pharmacological and non-pharmacological therapies for chronic pain is needed. Interventions allow patients with impaired urinary function to be reintroduced to society. For sexual dysfunction, it is necessary to discuss safe sex and behavioral changes. Regarding risk behaviors, it is necessary to guide the patient/family, adapt language to the education level of these individuals, and help them better accept the condition, among other guidelines. Conclusion: The development of a nursing care plan for PLHTLV is essential for preventing the rapid progression of disease and the improvement of the quality of life of PLHTLV and should be included in the multidisciplinary approach to the secondary level of prevention of HTLV-1.

Impact of screening on cervical cancer incidence and mortality in a Northern Brazilian city.

Objective: To analyse the impact of screening actions on the incidence and mortality rates of cervical cancer (CC) in the city of Belém, Brazil. Methods: Based on the cancer registry data from 1998 to 2017, collected from the Belém Population-Based Cancer Registry, combined with local population data for the interval 1998-2017, CC incidence and mortality were calculated. The Segi world population 1960 was used for age-standardised incidence/mortality rates. Results: In the period analysed, there were 4,469 new cases and 1,660 deaths from CC. The median age at diagnosis of invasive cases was 51 years. The age-adjusted incidence rate decreased from 18.65/100,000 in 1998 to 11.79/100,000 in 2017, despite the increase observed in the first 5 years of the historical series, while there was stability in mortality rates in the same time lapse. Conclusion: CC is still one of the most common malignant tumours that threaten public health in northern Brazil. The trend of the disease depends on comprehensive prevention and control strategies regarding the local situation and age groups, with emphasis on the organisation of the screening programme and vaccination against human papillomavirus.

Aquatic physiotherapy: a vestibular rehabilitation option.

INTRODUCTION: Vestibular rehabilitation is a fundamental resource for vestibular symptom control. Its performance in the aquatic environment is considered safe for the physical activities of the elderly, because they act simultaneously on musculoskeletal disorders and balance improvement. OBJECTIVE: To evaluate the effects of an aquatic physiotherapy protocol in individuals with peripheral vestibular alterations. METHODS: This was an interventional case study with a paired intentional sample of four subjects, who were selected for convenience. The subjects, all of them diagnosed with peripheral vestibulopathy, were submitted to twelve sessions of aquatic physiotherapy for vestibular rehabilitation, being evaluated for dizziness in three moments: initial, after six sessions and at the end of the sessions. The tests applied were: unipodal support to measure static balance, the Fukuda stepping test, which estimates the dynamic balance and the dizziness handicap inventory protocol, aimed at verifying how dizziness influences daily life. RESULTS: When analyzing the static balance, initially the individuals were in the adaptive and abnormal dimensions, and all reached normality at the end of the protocol. Regarding the dynamic balance, the individuals initially showed marked impairment in the angular deviation, mainly to the side of pathology (75% to the left and 25% to the right), achieving improvement at the end of the study. However, it failed to reach statistical significance. The dizziness handicap inventory showed a statistically significant difference in its totality (p = 0.0414), which addresses the physical, functional and emotional factors. CONCLUSION: In conclusion, the aquatic physiotherapy protocol for vestibular rehabilitation of patients with peripheral impairment was positively assessed by the participants, considering the improvement in dizziness (static and dynamic) and its impact on daily activities.

Croton cajucara crude extract and isolated terpenes: activity on Trypanosoma cruzi.

Croton cajucara is a plant found in the Amazon region and is known for its medicinal properties. The effects of the methanolic extract of the stem bark of C. cajucara (MCC) and of the isolated terpenes, trans-dehydrocrotonin (t-DCTN) and acetyl aleuritolic acid (AAA), were investigated using four isolates of Trypanosoma cruzi. In assays with trypomastigotes, the extract was more active than the isolated compounds, presenting IC(50) in the range of 10 to 50 µg/mL. The trypanocidal effect of MCC, AAA and benznidazole was significantly higher in the GLT291 and C45 strains, which were recently isolated from wild animals. MCC and AAA caused a dose-dependent inhibition of epimastigote proliferation. In assays using intracellular amastigotes, AAA and MCC reduced the percent of infection and the endocytic index after 96 h of treatment, at concentrations that were non-toxic to the host cells. MCC inhibited the trypanothione reductase pathway in both epimastigotes and trypomastigotes of all the subpopulations. The absence of AAA activity on the trypanothione reductase pathway in epimastigotes of Dm28c suggests heterogeneity of the biochemical profile between this clone and the three strains. Epimastigotes and trypomastigotes (GLT291) were treated for 24 h with MCC or AAA, and both induced alterations of the plasma membrane, while AAA-treated epimastigotes also displayed mitochondrial damage.

Plant Chromosome-Specific Probes by Microdissection of a Single Chromosome: Is That a Reality?

Painting plant chromosomes through chromosomal in situ suppression (CISS) hybridization has long been considered impracticable. Seeking to build specific and complex probes from a single microdissected chromosome, we employed human chromosomes as models to standardize all the necessary steps for application in plants. Human metaphases were used to define the adequate conditions for microdissection, chromosome DNA amplification and labeling through degenerate oligonucleotide-primed PCR, and in situ hybridization stringency. Subsequently, these methodologies were applied in the plant species Zea mays (chromosome 1) and Capsicum annuum (chromosome 7 or 8). The high quality of human and plant cytogenetic preparations and the meticulous standardization of each step, especially the most critical ones - microdissection and first round of DNA amplification - were crucial to eliminate the signs of non-specific hybridization and for direct application in plants. By overcoming these challenges, we obtained chromosome-specific probes, which allowed to achieve a clear and uniform painting of the entire target chromosomes with little or no background, evidencing their complexity and specificity. Despite the high amount of ubiquitous repetitive sequences in plant genomes, the main drawback for chromosome painting, we successfully employed our methodology on two plant species. Both have more than 80% repetitive sequences, which is compared to the human genome (66-69%). This is the first time that plant chromosome-specific probes were successfully obtained from a single A mitotic or meiotic microdissected chromosome. Thereby, we assume that chromosome painting through microdissection and CISS hybridization can now be considered a reality in the field of plant cytogenetics.

Limitations in daily activities, risk awareness, social participation, and pain in patients with HTLV-1 using the SALSA and Participation scales.

BACKGROUND: Tropical spastic paraparesis or HTLV-associated myelopathy (TSP/HAM) may prevent, limit or restrict the performance of daily living activities, and as a consequence, several aspects of life are affected. OBJECTIVE: The aim of this study was to evaluate activity limitations, risk awareness, social participation, quality of life, and pain in individuals infected with HTLV-1. METHODS: This was an observational, descriptive, analytical, cross-sectional study with a quantitative approach. An interview questionnaire, the Screening of Activity Limitation and Safety Awareness (SALSA) scale, the Participation scale, a quality of life questionnaire (SF-36) and the Brief Pain Inventory were used. RESULTS: A total of 55 patients with HTLV-1 were interviewed (62% asymptomatic and 38% symptomatic). In both groups, there was a higher frequency of patients aged 41-50 years old (35.3% asymptomatic and 38.1% symptomatic), with complete secondary education (47.1% asymptomatic and 42.9% symptomatic), and married (64.7% asymptomatic and 52.4% symptomatic). Of the symptomatic patients, 33.3% were retired; among asymptomatic patients, 20.6% performed domestic activities. The majority of patients in both groups had not received blood transfusions. Sexual intercourse was still practiced by patients. After assessment, asymptomatic patients had no activity limitations (64.7%), and symptomatic patients presented limitations (90.5%). None of the groups showed good risk awareness. There was no restriction on social participation in 97.1% of asymptomatic patients and in 52.4% among symptomatics. Both groups complained of pain, being more frequent in the lumbar spine in asymptomatic patients and in the knees in symptomatic patients. Pain was more severe in symptomatic patients and affected aspects of quality of life. CONCLUSION: The clinical follow-up instruments must be adopted by healthcare professionals to monitor new symptoms so as to avoid the onset of limitations identified in symptomatic patients, in addition to enabling continuous surveillance of asymptomatic patients.

Pilates exercise improves the clinical and immunological profiles of patients with human T-cell lymphotropic virus 1 associated myelopathy: A pilot study.

BACKGROUND: HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is an infectious chronic-inflammatory disease, which can lead to lower limb motions. METHODS: The study evaluated the effects of serial Pilates exercises on the clinical and immunological profiles of patients with HAM/TSP. Eight patients with ages ranging from 39 to 70 years old (2 males and 6 females), 2 wheelchair users and 6 with compromised gait, were evaluated. The patients were submitted to 20 Pilates sessions for 10 weeks. Data were collected at 3 time points (beginning of the study, after Pilates sessions and after 10 weeks without Pilates) and consisted of evaluations of the pain level, spasticity, motor strength, balance, mobility, functional capacity, quality of life and quantification of IFN-γ, IL-10 and IL-9 cytokines levels. RESULTS: After the Pilates sessions, significant improvements in pain level, static and dynamic balance, trunk control, mobility and quality of life were observed, with simultaneous and significant reductions in the serum levels of the cytokines IFN-γ and IL-10. However, after 10 weeks without Pilates, there were significant changes in terms of increasing pain and regression of mobility, with no changes in strength, spasticity, functional capacity in any of the periods of the study. CONCLUSIONS: The results suggest that Pilates may be a promising auxiliary physical therapy for patients with HAM/TSP.

Physiological and metabolic responses to hypersalinity reveal interpopulation tolerance in the green macroalga Ulva compressa with different pollution histories.

There is scarce investigation addressing interpopulation tolerance responses to address the influence of a history of chronic stress exposure, as that occurring in polluted environments, in photoautotrophs. We evaluated ecophysiological (photosynthetic activity) and metabolic (oxidative stress and damage) responses of two populations of green macroalga Ulva compressa from polluted (Ventanas) and non-polluted (Cachagua) localions of central Chile, and exposed to controlled hypersalinity conditions of 32 (control), 42, 62 and 82 psu (practical salinity units) for 6 h, 48 h and 6 d. Both primary production (ETRmax) and photosynthetic efficiency (αETR) were generally higher in the population from Cachagua compared to Ventanas at all times and salinities. Moreover, at most experimental times and salinities the population from Ventanas had greater levels of H2O2 and lipid peroxidation that individuals from Cachagua. Total ascorbate was higher in the population of Cachagua than Ventanas at 42 and 82 psu after 6 and 48 h, respectively, while at 6 d concentrations were similar between both populations at all salinities. Total glutathione was greater in both populations after 6 h at all salinities, but at 48 h its concentrations were higher only in the population from Cachagua, a trend that was maintained at 6 d under 82 psu only. Reduced and oxidized ascorbate (ASC and DHA, respectively) and glutathione (GSH and GSSG, respectively) demonstrated similar patterns between U. compressa populations, with an increase oxidation with greater salinities but efficient recycling to maintain sufficient batch of ASC and GSH. When assessing the expression of antioxidant enzymes catalase (CAT), superoxide dismutase (SOD) and dehydroascorbate reductase (DHAR), while the population of Ventanas displayed a general trend of upregulation with increasing salinities along the experiments, U. compressa from Cachagua revealed patterns of downregulation. Results demonstrated that although both populations were still viable after the applied hypersalinities during all experimental times, biological performance was usually more affected in the population from the Ventanas than Cachagua, likely due to a depressed baseline metabolism after a long history of exposition to environmental pollution.

HTLV-I induces lesions in the pulmonary system: A systematic review.

This study analyzed the relationship between infection by human T-cell lymphotropic virus type 1 (HTLV-1) and changes in the pulmonary system. Cohort and case-control study models that analyzed a causal association between HTLV-1 and changes in the pulmonary system were considered. There were no restrictions on language and publication period. The study was registered in the PROSPERO systematic analysis database (Protocol No. CRD42017078236) and was prepared according to the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The following databases were used: PubMed, BVS Regional Portal, Embase, CINAHL and Web of Science. We utilized the Newcastle-Ottawa Scale to assess the methodological quality of published studies and the Kappa coefficient to assess the agreement level between two reviewers. Of the total 1156 studies retrieved by the search strategy, 28 were considered potentially eligible (Kappa test = 0.928). Of the 28 studies, three fully met the inclusion criteria. These indicated that pulmonary lesions, such as bronchiectasis and bronchitis/bronchiolitis, were observed in patients with HTLV-1, with high-resolution computed tomography of the chest being the main method of diagnostic investigation. The analyzed cohort and case-control studies indicated an etiological relationship between HTLV-1 infection and the presence of lung lesions, with emphasis on bronchiectasis in the presence of high viral loads, as well as a higher mortality in these individuals compared with the general population.

In vitro sodium nitroprusside-mediated toxicity towards Leishmania amazonensis promastigotes and axenic amastigotes.

Leishmania parasites survive despite exposure to the toxic nitrosative oxidants during phagocytosis by the host cell. In this work, the authors investigated comparatively the resistance of Leishmania amazonensis promastigotes and axenic amastigotes to a relatively strong nitrosating agent that acts as a nitric oxide (NO) donor, sodium nitroprusside (SNP). Results demonstrate that SNP is able to decrease, in vitro, the number of L. amazonensis promastigotes and axenic amastigotes in a dose-dependent maner. Promastigotes, cultured in the presence of 0.25, 0.5, and 1 mmol L(-1) SNP for 24 h showed about 75% growth inhibition, and 97-100% when the cultures were treated with >2 mmol L(-1) SNP. In contrast, when axenic amastigotes were growing in the presence of 0.25-8 mM SNP added to the culture medium, 50% was the maximum of growth inhibition observed. Treated promastigotes presented reduced motility and became round in shape further confirming the leishmanicidal activity of SNP. On the other hand, axenic amastigotes, besides being much more resistant to SNP-mediated cytotoxicity, did not show marked morphological alteration when incubated for 24 h, until 8 mM concentrations of this nitrosating agent were used. The cytotoxicity toward L. amazonensis was attenuated by reduced glutathione (GSH), supporting the view that SNP-mediated toxicity triggered multiple oxidative mechanisms, including oxidation of thiols groups and metal-independent oxidation of biomolecules to free radical intermediates.