Benefits and costs of immune memory in Rhodnius prolixus against Trypanosoma cruzi.

There is increasing evidence supporting the immune memory in invertebrates, but the studies are relatively neglected in insect vectors other than mosquitoes. Therefore, we tested two hypotheses: 1) Rhodnius prolixus insects possess immune memory against Trypanosoma cruzi, and 2) their immune memory is costly. The Dm28c and Y strains of T. cruzi were used, the former being more infective than the latter. On the one hand, the triatomines subjected to dual challenges with the Dm28c strain did not show significant differences in survival than those of the heterologous challenge groups control-Dm28c and Y-Dm28c. On the other hand, the insects survived longer after a dual Y-Y challenge than after the corresponding heterologous challenge (control-Y). The Y-Y, Dm28c-Y, and naïve groups showed similar survival. There was more prolonged survival following the Y-Y versus Dm28c-Dm28c dual challenge. The Dm28c-Dm28c group exhibited moulting sooner than the control-Dm28c or naïve group. In contrast, there were no differences in the probability of moulting between the Y-Y and naïve groups. The results suggest that triatomines have immune memory against the Y but not the Dm28c strain. Further investigation on triatomine and T. cruzi interaction is needed to determine if infectivity accelerates or delay growth due to innate immune memory.

Electrophoresis and spectrometric analyses of adaptation-related proteins in thermally stressed Chromobacterium violaceum.

Chromobacterium violaceum is a Gram-negative proteobacteria found in water and soil; it is widely distributed in tropical and subtropical regions, such as the Amazon rainforest. We examined protein expression changes that occur in C. violaceum at different growth temperatures using electrophoresis and mass spectrometry. The total number of spots detected was 1985; the number ranged from 99 to 380 in each assay. The proteins that were identified spectrometrically were categorized as chaperones, proteins expressed exclusively under heat stress, enzymes involved in the respiratory and fermentation cycles, ribosomal proteins, and proteins related to transport and secretion. Controlling inverted repeat of chaperone expression and inverted repeat DNA binding sequences, as well as regions recognized by sigma factor 32, elements involved in the genetic regulation of the bacterial stress response, were identified in the promoter regions of several of the genes coding proteins, involved in the C. violaceum stress response. We found that 30 °C is the optimal growth temperature for C. violaceum, whereas 25, 35, and 40 °C are stressful temperatures that trigger the expression of chaperones, superoxide dismutase, a probable small heat shock protein, a probable phasing, ferrichrome-iron receptor protein, elongation factor P, and an ornithine carbamoyltransferase catabolite. This information improves our comprehension of the mechanisms involved in stress adaptation by C. violaceum.

[Sociodemographic, clinical and ultrasound characterization of thyroid nodule pathology and its association with malignancy in a Colombian high-complexity center]. / Caracterización sociodemográfica, clínica y ecográfica de la enfermedad de nódulos tiroideos y su relación con la malignidad en un centro de alta complejidad colombiano.

BACKGROUND AND OBJECTIVE: Thyroid nodules are among the most frequent conditions, with a 10% risk of malignancy. The objective is to describe the frequency of demographic, clinical, and ultrasonographic characteristics of thyroid nodule pathology in adults and to explore the relationship with tumor malignancy. METHODS: An analytical, retrospective cross-sectional study in adults with thyroid nodules and nodular fine-needle aspiration performed in adult patients from a Colombian reference center between 2009-2019. Data were obtained from the clinical history, descriptive measures of the patient's demographic, clinical, and ultrasound variables were estimated, and their relationship with the malignancy of the tumor was explored. RESULTS: A total of 445 patients and 515 nodules were included. The median age was 55 years (IQR 44-64), 86.8% of women, and 54.8% had a single lesion. Percentages of 80.2 and 19.8 were benign and malignant nodules, with a median of 15.7mm (IQR 11-25) and 12.7mm (IQR 8.5-18.3), respectively (p<0.001). Hypothyroidism and levothyroxine consumption were higher in those with malignant nodules (p<0.001). The echographic characteristics were statistically different between the nodules. In the malignant ones, there was a higher frequency of solid composition, hypoechogenicity, and irregular margins. In contrast, in the benign ones, the absence of echogenic focus stood out (p<0.001). CONCLUSION: The ultrasound characteristics are essential to define the risk of malignancy of a thyroid nodule. Therefore, considering the most frequent ones can help in the most appropriate approach to primary care.

The innate immune response of triatomines against Trypanosoma cruzi and Trypanosoma rangeli with an unresolved question: Do triatomines have immune memory?

The present work aimed to review the immune response from different triatomines against Trypanosoma cruzi and Trypanosoma rangeli and propose the study of immune memory in such insects. Trypanosoma use triatomines as vectors to reach and infect mammals. A key question to be answered about vector-parasite interaction is why the immune defense and resistance of the insect against the parasites vary. Up to date data shows that the defense of triatomines against parasites includes cellular (phagocytosis, nodulation and encapsulation) and humoral (antimicrobial peptides, phenoloxidase and reactive oxygen and nitrogen species) responses. The immune response varies depending on the triatomine species, the trypanosome strain and species, and the insect intestinal microbiota. Despite significant advances to understand parasite-insect interaction, it is still unknown if triatomines have immune memory against parasites and if this memory may derive from tolerance to parasites attack. Therefore, a closer study of such interaction could contribute and establish new proposals to control the parasite at the vector level to reduce parasite transmission to mammals, including men. For instance, if immune memory exists in the triatomines, it would be interesting to induce weak infections in insects to find out if subsequent infections are less intense and if the insects succeed in eliminating the parasites.

Immune depression in Rhodnius prolixus by seco-steroids, physalins.

A comparative study of the effects of physalins, seco-steroidal substances of Physalis angulata (Solanaceae), on the immune reactions of R. prolixus was carried out. Ecdysis and mortality were not affected by treatment with physalins B, D, F or G (1-10 microg/ml of blood meal). R. prolixus larvae fed with blood containing physalins and inoculated with 1 microl of Enterobacter cloacae beta12 (5 x 10(3)/insect) exhibited mortality rates three times higher than controls. The insects treated with physalin B, and F (1 microg/ml) and inoculated with E. cloacae beta12 showed significant differences on lysozyme activity in the hemolymph compared to untreated insects. Furthermore, physalin D (1 microg/ml) significantly reduced the antibacterial activity. Concerning cellular immune reactions, all insects treated with physalins (1 microg/ml), exhibited drastic reductions in the quantity of yeast cell-hemocyte binding and subsequent internalization. Insects inoculated with bacteria and treated with physalins B, F and G showed reductions of microaggregate formation but physalin D did not. Physalins B and F also reduced total hemocyte count in the hemolymph. These results suggest that, in different ways, probably due to their different chemical structures, physalin B, D, F and G are immunomodulatory substances for the bloodsucking insect, R. prolixus.

Rhodnius prolixus: from physiology by Wigglesworth to recent studies of immune system modulation by Trypanosoma cruzi and Trypanosoma rangeli.

This review is dedicated to the memory of Professor Sir Vincent B. Wigglesworth (VW) in recognition of his many pioneering contributions to insect physiology which, even today, form the basis of modern-day research in this field. Insects not only make vital contributions to our everyday lives by their roles in pollination, balancing eco-systems and provision of honey and silk products, but they are also outstanding models for studying the pathogenicity of microorganisms and the functioning of innate immunity in humans. In this overview, the immune system of the triatomine bug, Rhodnius prolixus, is considered which is most appropriate to this dedication as this insect species was the favourite subject of VW's research. Herein are described recent developments in knowledge of the functioning of the R. prolixus immune system. Thus, the roles of the cellular defences, such as phagocytosis and nodule formation, as well as the role of eicosanoids, ecdysone, antimicrobial peptides, reactive oxygen and nitrogen radicals, and the gut microbiota in the immune response of R. prolixus are described. The details of many of these were unknown to VW although his work gives indications of his awareness of the importance to R. prolixus of cellular immunity, antibacterial activity, prophenoloxidase and the gut microbiota. This description of R. prolixus immunity forms a backdrop to studies on the interaction of the parasitic flagellates, Trypanosoma cruzi and Trypanosoma rangeli, with the host defences of this important insect vector. These parasites remarkably utilize different strategies to avoid/modulate the triatomine immune response in order to survive in the extremely hostile host environments present in the vector gut and haemocoel. Much recent information has also been gleaned on the remarkable diversity of the immune system in the R. prolixus gut and its interaction with trypanosome parasites. This new data is reviewed and gaps in our knowledge of R. prolixus immunity are identified as subjects for future endeavours. Finally, the publication of the T. cruzi, T. rangeli and R. prolixus genomes, together with the use of modern molecular techniques, should lead to the enhanced identification of the determinants of infection derived from both the vector and the parasites which, in turn, could form targets for new molecular-based control strategies.

Impact of Trypanosoma cruzi on antimicrobial peptide gene expression and activity in the fat body and midgut of Rhodnius prolixus.

BACKGROUND: Rhodnius prolixus is a major vector of Trypanosoma cruzi, the causative agent of Chagas disease in Latin America. In natural habitats, these insects are in contact with a variety of bacteria, fungi, virus and parasites that they acquire from both their environments and the blood of their hosts. Microorganism ingestion may trigger the synthesis of humoral immune factors, including antimicrobial peptides (AMPs). The objective of this study was to compare the expression levels of AMPs (defensins and prolixicin) in the different midgut compartments and the fat body of R. prolixus infected with different T. cruzi strains. The T. cruzi Dm 28c clone (TcI) successfully develops whereas Y strain (TcII) does not complete its life- cycle in R. prolixus. The relative AMP gene expressions were evaluated in the insect midgut and fat body infected on different days with the T. cruzi Dm 28c clone and the Y strain. The influence of the antibacterial activity on the intestinal microbiota was taken into account. METHODS: The presence of T. cruzi in the midgut of R. prolixus was analysed by optical microscope. The relative expression of the antimicrobial peptides encoding genes defensin (defA, defB, defC) and prolixicin (prol) was quantified by RT-qPCR. The antimicrobial activity of the AMPs against Staphylococcus aureus, Escherichia coli and Serratia marcescens were evaluated in vitro using turbidimetric tests with haemolymph, anterior and posterior midgut samples. Midgut bacteria were quantified using colony forming unit (CFU) assays and real time quantitative polymerase chain reaction (RT-qPCR). RESULTS: Our results showed that the infection of R. prolixus by the two different T. cruzi strains exhibited different temporal AMP induction profiles in the anterior and posterior midgut. Insects infected with T. cruzi Dm 28c exhibited an increase in defC and prol transcripts and a simultaneous reduction in the midgut cultivable bacteria population, Serratia marcescens and Rhodococcus rhodnii. In contrast, the T. cruzi Y strain neither induced AMP gene expression in the gut nor reduced the number of colony formation units in the anterior midgut. Beside the induction of a local immune response in the midgut after feeding R. prolixus with T. cruzi, a simultaneous systemic response was also detected in the fat body. CONCLUSIONS: R. prolixus AMP gene expressions and the cultivable midgut bacterial microbiota were modulated in distinct patterns, which depend on the T. cruzi genotype used for infection.

[Spontaneous breathing trial in chronic obstructive pulmonary disease: continuous positive airway pressure (CPAP) versus T-piece]. / Ensayo de respiración espontánea en pacientes con enfermedad pulmonar obstructiva crónica: presión positiva continua de la vía aérea (CPAP) versus Tubo en T.

OBJECTIVE: To determine if the spontaneous breathing trial (SBT) with continuous positive airway pressure (CPAP) is superior to SBT with a T-piece in patients with Chronic Obstructive Pulmonary Disease (COPD). DESIGN: A blind clinical test with random distribution. SETTING: Three medical-surgical intensive care units. PATIENTS: A random sample of 50 patients with COPD who had received mechanical ventilation for more than 48 hours and who were considered to fulfill weaning criteria: resolution of the exacerbation of the COPD disease, Glasgow scale >10, temperature ≤ 38°C, PaO(2) /FiO(2) quotient >150 with an external PEEP ≤5cm H(2)O and FiO(2) ≤ to 50%, hemoglobin >10g/dl, no need for vasoactive drugs (except for dopamine ≤5µg/kg/min or dobutamine ≤5µg/kg/min) or for sedative agents and effective cough. INTERVENTION: A 30-minute spontaneous respiration trial with T-piece system or CPAP. VARIABLES: Successful weaning from mechanical ventilation, successful SBT, reintubation and intrinsic PEEP. RESULTS: Out of 25 patients who were assigned to the T-tube group, 18 successfully completed the trial and were extubated; 3 of them requiring reintubation. Out of 25 patients who were assigned to the CPAP group, 19 were extubated and none of them required reintubation. There was successful weaning from mechanical ventilation in 76% in SBT-CPAP vs 60% in SBT-TT (relative risk 1.27; 95% confidence interval 0.86 to 1.87). CONCLUSION: In a COPD patient cohort, the performance of spontaneous breathing with CPAP showed a tendency to better outcome than with T-Piece, however, further research is needed.

Physalin B inhibits Rhodnius prolixus hemocyte phagocytosis and microaggregation by the activation of endogenous PAF-acetyl hydrolase activities.

The effects of physalin B (a natural secosteroidal chemical from Physalis angulata, Solanaceae) on phagocytosis and microaggregation by hemocytes of 5th-instar larvae of Rhodnius prolixus were investigated. In this insect, hemocyte phagocytosis and microaggregation are known to be induced by the platelet-activating factor (PAF) or arachidonic acid (AA) and regulated by phospholipase A(2) (PLA(2)) and PAF-acetyl hydrolase (PAF-AH) activities. Phagocytic activity and formation of hemocyte microaggregates by Rhodnius hemocytes were strongly blocked by oral treatment of this insect with physalin B (1mug/mL of blood meal). The inhibition induced by physalin B was reversed for both phagocytosis and microaggregation by exogenous arachidonic acid (10microg/insect) or PAF (1microg/insect) applied by hemocelic injection. Following treatment with physalin B there were no significant alterations in PLA(2) activities, but a significant enhancement of PAF-AH was observed. These results show that physalin B inhibits hemocytic activity by depressing insect PAF analogous (iPAF) levels in hemolymph and confirm the role of PAF-AH in the cellular immune reactions in R. prolixus.

Prevalência do medo de cair em uma população de idosos da comunidade e sua correlação com mobilidade, equilíbrio dinâmico, risco e histórico de quedas / Prevalence of fear of falling among a population of older adults and its correlation with mobility, dynamic balance, risk and history of falls

OBJETIVOS: Investigar a prevalência do medo de cair em uma população de idosos da comunidade e sua correlação com mobilidade, equilíbrio dinâmico, risco e histórico de quedas. MÉTODOS: Estudo transversal randomizado. Participaram do estudo 147 idosos com idades entre 60 e 92 anos, sendo 94 (65,95 por cento) mulheres e 53 (36,05 por cento) homens. O medo de cair foi avaliado usando FES-I-BRASIL (FIB), a mobilidade foi avaliada por meio do teste "Timed Up and go" (TUG), o risco de quedas, por meio do "Functional Reach Test" (FRT) e o equilíbrio dinâmico, pelo teste da Marcha Tandem (MT). RESULTADOS: Cento e trinta e três (90,48 por cento) idosos relataram medo de cair em pelo menos uma atividade, e 80 (54,42 por cento) dos idosos apresentaram histórico de quedas (HQ). A correlação de Pearson demonstrou resultado significante (p<0,001) do medo de cair com MT (r=-0,44248), FRT (r=-0,51562), HQ (r=0,54069), TUG (r=0,45738) e idade (r=0,39772). CONCLUSÕES: O presente estudo identificou alta prevalência de medo de cair nos idosos da comunidade, independente do HQ, e correlação significativa do medo de cair com mobilidade, equilíbrio dinâmico, risco e HQ.

OBJECTIVES: To investigate the prevalence of fear of falling among a population of older adults and its correlation with mobility, dynamic balance, risk and history of falls. METHODS: This was a randomized cross-sectional study. The participants were 147 older adults between the ages of 60 and 92: 94 women (65.95 percent) and 53 men (36.05 percent). Fear of falling was assessed using FES-I-BRAZIL (FIB); mobility, using the "timed up and go" (TUG) test; risk of falls, using the "functional reach test" (FRT); and dynamic balance, using the "tandem gait test"(TGT). RESULTS: One hundred and thirty-three older adults (90.48 percent) reported fear of falling in at least one activity and 80 older adults (54.42 percent) had a history of falls (HF). Pearson's correlation was statistically significant (p<0.001) between fear of falling and the TGT (r=-0.44248), FRT (r=-0.51562), HF (r=0.54069), TUG (r=0.45738) and age (r=0.39772). CONCLUSIONS: The present study identified high prevalence of fear of falling among older adults in the community, independent of their history of falls, and significant correlations between fear of falling and mobility, dynamic balance, risk and history of falls.