Leishmania amazonensis is one of leishmaniasis’ causative agents, a disease that has no cure and leads to the appearance of cutaneous lesions. Recently, our group showed that heme activates a Na+/K+ ...ATPase in these parasites through a signaling cascade involving hydrogen peroxide (H2O2) generation. Heme has a pro-oxidant activity and signaling capacity, but the mechanism by which this molecule increases H2O2 levels in L. amazonensis has not been elucidated. Here we investigated the source of H2O2 stimulated by heme, ruling out the participation of mitochondria and raising the possibility of a role for a NADPH oxidase (Nox) activity. Despite the absence of a classical Nox sequence in trypanosomatid genomes, L. amazonensis expresses a surface ferric iron reductase (LFR1). Interestingly, Nox enzymes are thought to have evolved from ferric iron reductases because they share same core domain and are very similar in structure. The main difference is that Nox catalyses electron flow from NADPH to oxygen, generating reactive oxygen species (ROS), while ferric iron reductase promotes electron flow to ferric iron, generating ferrous iron. Using L. amazonensis overexpressing or knockout for LFR1 and heterologous expression of LFR1 in mammalian embryonic kidney (HEK 293) cells, we show that this enzyme is bifunctional, being able to generate both ferrous iron and H2O2. It was previously described that protozoans knockout for LFR1 have their differentiation to virulent forms (amastigote and metacyclic promastigote) impaired. In this work, we observed that LFR1 overexpression stimulates protozoan differentiation to amastigote forms, reinforcing the importance of this enzyme in L. amazonensis life cycle regulation. Thus, we not only identified a new source of ROS production in Leishmania, but also described, for the first time, an enzyme with both ferric iron reductase and Nox activities.
The tick fauna of Brazil is currently composed by 72 species. The state of Amazonas is the largest of Brazil, with an area of ≈ 19% of the Brazilian land. Besides its vast geographic area, only 19 ...tick species have been reported for Amazonas. Herein, lots containing ticks from the state of Amazonas were examined in three major tick collections from Brazil. A total of 5933 tick specimens were examined and recorded, comprising 2693 males, 1247 females, 1509 nymphs, and 484 larvae. These ticks were identified into the following 22 species:
Amblyomma cajennense
sensu lato,
Amblyomma calcaratum, Amblyomma coelebs, Amblyomma dissimile, Amblyomma dubitatum, Amblyomma geayi, Amblyomma goeldii, Amblyomma humerale, Amblyomma latepunctatun, Amblyomma longirostre, Amblyomma naponense, Amblyomma oblongoguttatum, Amblyomma ovale, Amblyomma rotundatum, Amblyomma scalpturatum, Amblyomma varium, Dermacentor nitens, Haemaphysalis juxtakochi, Ixodes
cf.
Ixodes fuscipes, Ixodes luciae, Rhipicephalus microplus, Rhipicephalus sanguineus
sensu lato. Ticks were collected from 17 (27.4%) out of the 62 municipalities that currently compose the state of Amazonas. The following four species are reported for the first time in the state of Amazonas:
A. coelebs, A. dubitatum
,
H. juxtakochi
, and
Ixodes
cf.
I. fuscipes.
The only tick species previously reported for Amazonas and not found in the present study is
Amblyomma parvum.
This study provides a great expansion of geographical and host records of ticks for the state of Amazonas, which is now considered to have a tick fauna composed by 23 species. It is noteworthy that we report 1391
Amblyomma
nymphs that were identified to 13 different species.
This work presents the dielectric properties of Ba
2
TiSi
2
O
8
in the Radiofrequency (RF) and Microwave (MW) regions. X-ray diffraction analysis showed that the material was obtained as a ...single-phase without the presence of spurious phases. Complex impedance spectroscopy demonstrated that there was no significant change of permittivity with temperature, whereas the dielectric loss was less than 1. Nyquist diagrams were modelled through an equivalent circuit using two associations of R-CPE related to the grain and the grain boundary effects. The MW analysis showed
ε′
r
= 11.01 and tan
δ
= 4.55 × 10
–2
, values that are close to the results obtained in the RF region. Moreover, the τ
f
value for Ba
2
TiSi
2
O
8
was equal to − 47 ppm/°C which is close to the values adequate for a microwave device application. The numerical simulation demonstrated the operation of the material as a Dielectric Resonator Antenna (DRA), where a reflection coefficient below − 10 dB, a realised gain of 6.739 dBi, a bandwidth of 452.96 MHz and a radiation efficiency around 100% were observed. The results indicate that Ba
2
TiSi
2
O
8
would be an interesting candidate in microwave operating devices in the C-band, as well as in devices operating in RF.
People living with Human Immunodeficiency Virus (HIV) are under risk for co-infection with SARS-CoV-2. This population may be more prone to complications from COVID-19 due to persistent inflammation ...caused by HIV and higher incidence of metabolic syndromes, cardiovascular diseases, and malignancies, as well as being considered elderly at 50 years of age. The objective of this study was to report SARS-CoV-2 infection frequency, clinical evolution, and mortality in HIV-positive patients on antiretroviral therapy.
The period of inquiry ranged from January to September 2020. Due to the social distance and the suspension of in-person medical care during the time of the investigation, we sent electronic questions about demographic, epidemiological, and clinical data to 403 HIV-infected patients.
Among 260 patients who answered the questionnaire, thirty-nine patients (15%) had suggestive symptoms and were tested for SARS-CoV-2 infection. Of this, 11 had positive results (32.4%) and no patient died of COVID-19 complications. Nine were male (3.4%), and the mean age of the patients with positive results was 43.2 years (± 9.6). 107 patients (41.1%) were over 50 years of age and their mean T-CD4+ cell count was 768. Eleven patients (4.2%) had a detectable HIV RNA viral load and 127 (48.8%) had comorbidities. These variables were not associated with an increased risk for infection.
The frequency of SARS-COV2 infection among HIV-infected is similar to the general population, and the clinical course is associated with the presence of comorbidities and not due to the HIV infection. However, new studies should be done to assess if this vulnerable population could answer the vaccine anti-SARS-Cov2.
Background. Maternal-fetal transferred dengue virus (DENV)-specific antibodies have been implicated in the immunopathogenesis of dengue during infancy. Methods. A prospective birth cohort was ...established in a dengue-endemic area in the Northeast Region of Brazil. DENV-specific immunoglobulin G (IgG) and DENV-1-4 serotype-specific neutralizing antibody (NAb) levels were assessed in 376 paired maternal and umbilical cord blood samples. The kinetics of enhancing activity by maternally acquired DENV antibodies was determined in serum samples from children enrolled in the cohort. Results. Mothers were mostly immune to DENV-3 alone (53.7%) or combined with DENV-4 (30.6%). Levels of DENV-specific IgG, DENV-3 NAbs, and DENV-4 NAbs were significantly higher in newborns than in their respective mothers. Mothers immune to a single serotype transferred greater levels of DENV-specific IgG (P= .02) and DENV-3 NAbs (P = .04) than mothers immune to multiple DENV serotypes. Maternally acquired DENV-3 NAbs disappeared in > 90% of the children by the age of 4 months. The peak enhancing activity was detected by the age of 2 months (P < .0001) and rapidly declined by the age of 4 months (P = .0035). Conclusions. Unlike Asian infants, the enhancing activity of DENV infection by maternally transferred DENV antibodies occurs at earlier ages in Brazilian children. These findings might explain the low occurrence of severe dengue among infants in our setting.
Three of the possible approaches to optical temperature sensing of a thermographic phosphor were formally compared in upconversion (UC) of Er3+ and Yb3+ doped lanthanum orthoniobate (LNO) phosphor. ...The three approaches used in the study were namely fluorescence intensity ratio (FIR) of thermally coupled levels (TCL), Valley to Peak ratio (VPR) and the ratio of non-thermally coupled levels (NTCL), respectively. The TCLs in the study were the ratio of intensities of 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 UC transitions of Er3+ ion. VPR method was verified within 2H9/2 → 4I15/2 transition of Er3+ UC. The other ratios of transitions which are not fit in TCL were investigated through NTCL technique. Ratios of several sets of transitions namely 4S3/2 → 4I15/2/2H9/2 → 4I15/2, 4S3/2 → 4I15/2/2I9/2 → 4I15/2, 4S3/2 → 4I15/2/4F9/2 → 4I15/2, 4F7/2 → 4I15/2/2H11/2 → 4I15/2, 2H11/2 → 4I15/2/4I9/2 → 4I15/2 and 2H11/2 → 4I15/2/2G11/2 were considered for NTCL technique. Moreover, the effect of temperature in the emission color was analyzed and a change from yellow (0.3310; 0.5990) to green (0.2590; 0.6740) was observed when the temperature rise has been increased from 14 to 300 K. Results obtained indicate that the LNO:Er3+/Yb3+ phosphor could be employed in optical thermometry and this phosphor would be a candidate with high potential as sensor operating from low to room temperature using TCL, VPR and/or NTCL methods. The most prominent sensing technique in the case of LNO:Er/Yb material among the three techniques is found to be NTCL with the high relative sensitivity of 1.19% K−1 at 300 K.
•Upconversion of LaNbO4:Er3+/Yb3+ being considered for temperature sensing.•Observation of three different fluorescence sensing techniques in single material.•Fluorescence Intensity Ratio (FIR) of all the three techniques estimated.•Non-thermally coupled levels being prominent compared to thermally coupled and valley to peak ratios.
Influence of the geometry on the numerical simulation of the cooling kinetics of cucumbers Silva, W.P., Universidade Federal de Campina Grande (Brazil). Dept. de Física; Silva, C.M.D.P.S., Universidade Federal de Campina Grande (Brazil). Dept. de Física; Nascimento, P.L., Universidade Federal de Campina Grande (Brazil). Dept. de Física ...
Spanish journal of agricultural research : SJAR,
03/2011
Journal Article
Peer reviewed
Open access
En este trabajo se ha estudiado el efecto de la representación geométrica de los pepinos en la simulación numérica de su cinética de enfriamiento. Se ha supuesto que el modelo de difusión con la ...condición de frontera de tercera clase describe satisfactoriamente el enfriamiento y que los parámetros termofísicos son constantes durante el proceso. Las geometrías utilizadas para representar el pepino son cilindro infinito, cilindro finito y elipsoide. La ecuación de difusión se resolvió a través del método de volumen finito, con una formulación totalmente implícita, utilizando coordenadas cilíndricas y generalizadas. El coeficiente de transferencia de calor por convección y la difusividad térmica fueron determinados a través de la optimización, utilizando el método inverso. El mejor modelo en la representación de la forma del pepino fue el elipsoide, pero el tiempo exigido para su optimización fue cerca de 66 veces mayor que el tiempo para el cilindro infinito.
In this paper, the effect of the geometric representation of cucumbers on the numerical simulation of its cooling kinetics is studied. It is supposed that the diffusion model with boundary condition of the third kind satisfactorily describes the cooling, and that the thermo-physical parameters are constant during the process. The geometries used to represent the cucumber are: infinite cylinder, finite cylinder, and ellipsoid. The diffusion equation was solved through the finite volume method, with a fully implicit formulation, using cylindrical and generalized coordinates. The convective heat transfer coefficient and the thermal diffusivity were determined through optimization, using the inverse method. The best model in the representation of the cucumber's shape was the ellipsoid, but the time demanded in its optimization was about 66 times greater than the time for the infinite cylinder.
Pompe disease (PD) is a potentially lethal illness involving irreversible muscle damage resulting from glycogen storage in muscle fiber and activation of autophagic pathways. A promising therapeutic ...perspective for PD is enzyme replacement therapy (ERT) with the human recombinant enzyme acid alpha-glucosidase (Myozyme®). The need to organize a diagnostic flowchart, systematize clinical follow-up, and establish new therapeutic recommendations has become vital, as ERT ensures greater patient longevity. A task force of experienced clinicians outlined a protocol for diagnosis, monitoring, treatment, genetic counseling, and rehabilitation for PD patients. The study was conducted under the coordination of REBREPOM, the Brazilian Network for Studies of PD. The meeting of these experts took place in October 2013, at L'Hotel Port Bay in São Paulo, Brazil. In August 2014, the text was reassessed and updated. Given the rarity of PD and limited high-impact publications, experts submitted their views.
Aim
To detect cells expressing the stem cell marker ALDH1 (aldehyde dehydrogenase1) in the pulp of human permanent teeth and to investigate the expression of ALDH1 in isolated dental pulp cells.
...Methodology
Pulp tissue was collected and processed for immunohistochemistry to detect ALDH1‐, STRO‐1‐ and CD90‐positive cells. In addition, cells were isolated and analysed by flow cytometry for ALDH1 activity and for the cell surface markers CD44, CD73, CD90, STRO‐1 and CD45. Cells were also examined for multidifferentiation capacity. Within these cells, an ALDH1+ cell subpopulation was selected and evaluated for multidifferentiation capacity.
Results
The immunohistochemistry analyses showed that ALDH1‐, CD90‐ and STRO‐1‐positive cells were located mainly in the perivascular areas and nerve fibres of dental pulps. Cells on the fifth passage had high expression for CD44, CD73 and CD90, whereas moderate labelling was observed for STRO‐1 and ALDH1 in flow cytometry analysis. On the same passages, cells were able to differentiate into osteogenic, adipogenic and chondrogenic lineages. The ALDH1+ cell subpopulation also demonstrated multilineage differentiation ability.
Conclusions
Dental pulp stem cells reside in the vicinity of blood vessels and nerve fibres, indicating the possible existence of more than one stem cell niche in dental pulps. Furthermore, ALDH1 was expressed by isolated dental pulp cells, which had mesenchymal stem cell characteristics. Thus, it can be suggested that ALDH1 may be used as a DPSC marker.
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