Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 6 de 6
Filtrar
1.
Sensors (Basel) ; 23(15)2023 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-37571680

RESUMO

A novel graphene antenna composed of a graphene dipole and four auxiliary graphene sheets oriented at 90∘ to each other is proposed and analyzed. The sheets play the role of reflectors. A detailed group-theoretical analysis of symmetry properties of the discussed antennas has been completed. Through electric field control of the chemical potentials of the graphene elements, the antenna can provide a quasi-omnidirectional diagram, a one- or two-directional beam regime, dynamic control of the beam width and, due to the vertical orientation of the dipole with respect to the base substrate, a 360∘ beam steering in the azimuth plane. An additional graphene layer on the base permits control of the radiation pattern in the θ-direction. Radiation patterns in different working states of the antenna are considered using symmetry arguments. We discuss the antenna parameters such as input reflection coefficient, total efficiency, front-to-back ratio, and gain. An equivalent circuit of the antenna is suggested. The proposed antenna operates at frequencies between 1.75 THz and 2.03 THz. Depending on the active regime defined by the chemical potentials set on the antenna graphene elements, the maximum gain varies from 0.86 to 1.63.

2.
Mediators Inflamm ; 2021: 4651891, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33790690

RESUMO

Transforming growth factor beta (TGF-ß) is a cytokine with important involvement in biological processes related to the pathogenesis of sickle cell disease (SCD), including endothelial and vascular dysfunction, inflammation, and hematopoietic homeostasis. This study is aimed at investigating associations between levels of TGF-ß1 and classical laboratory biomarkers and inflammatory mediators, as well as the tissue inhibitor of metalloproteases-1 (TIMP-1) and matrix metalloproteinase-9 (MMP-9), in pediatric patients (n = 123) with SCD in steady state: 84 with sickle cell anemia (HbSS) and 39 with hemoglobin SC disease (HbSC). A healthy control (HC) group of 59 individuals was also included. Hematological and biochemical analyses were carried out using electronic methods. TGF-ß1, TIMP-1, and MMP-9 plasma quantifications were performed by ELISA. TGF-ß1 plasma levels were higher in HbSS individuals than in HbSC and HC. In individuals with HbSS, TGF-ß1 levels were positively correlated with red blood cells, hemoglobin, hematocrit, platelets, and TIMP-1. In addition, HbSS individuals with TGF-ß1 levels above the median (≥72.29 ng/mL) also presented increased monocyte counts and decreased albumin levels. In patients with HbSC, TGF-ß1 levels were positively correlated with leukocytes, eosinophils, lymphocytes, monocytes, and platelets, as well as levels of TIMP-1, VLDL-C, triglycerides, heme, and AST. Additionally, HbSC individuals with TGF-ß1 levels above the median (≥47.80 ng/mL) presented increased leukocyte and platelet counts, as well as increased levels of triglycerides, VLDL-C, MMP-9, and TIMP-1, and decreased HDL-C. Our findings suggest that TGF-ß1 may play important roles in vascular remodeling, vasculopathy, angiogenesis, and inflammation in pediatric patients with SCD.


Assuntos
Anemia Falciforme , Hemólise , Fator de Crescimento Transformador beta1 , Anemia Falciforme/diagnóstico , Biomarcadores/sangue , Criança , Humanos , Inflamação , Metaloproteinase 9 da Matriz , Inibidor Tecidual de Metaloproteinase-1/metabolismo , Fator de Crescimento Transformador beta1/sangue
3.
Mediators Inflamm ; 2020: 3185015, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33149723

RESUMO

Individuals with sickle cell disease (SCD) present both chronic and acute inflammatory events. The TGF-ß pathway is known to play a role in immune response, angiogenesis, inflammation, hematopoiesis, vascular inflammation, and cell proliferation. Polymorphisms in the transforming growth factor-beta receptor 3 (TGFBR3) gene have been linked to several inflammatory diseases. This study investigated associations between two TGFBR3 haplotypes and classical laboratory parameters, as well as clinical manifestations, in SCD. We found that individuals with the GG haplotype presented higher levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), triglycerides, non-HDL cholesterol, total proteins, and globulin than individuals with non-GG haplotypes. In addition, the GG haplotype was associated with a previous history of pneumonia. Individuals with the CGG haplotype presented increased plateletcrit, TC, LDL-C levels, and non-HDL cholesterol. The CCG haplotype was also associated with a previous history of pneumonia. Our findings suggest that individuals with the GG and CGG haplotypes of TGFBR3 present important alterations in lipid profile.


Assuntos
Anemia Falciforme/sangue , Anemia Falciforme/genética , Haplótipos , Hemoglobinas/metabolismo , Lipídeos/química , Polimorfismo de Nucleotídeo Único , Proteoglicanas/genética , Receptores de Fatores de Crescimento Transformadores beta/genética , Adolescente , Biomarcadores/metabolismo , Proliferação de Células , Criança , Colesterol/metabolismo , LDL-Colesterol , Feminino , Genótipo , Humanos , Inflamação , Desequilíbrio de Ligação , Masculino , Pneumonia/metabolismo , Prognóstico , Proteoglicanas/sangue , Receptores de Fatores de Crescimento Transformadores beta/sangue , Adulto Jovem
4.
Hemoglobin ; 41(2): 83-88, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28589738

RESUMO

Brazilian Quilombolas are communities composed of African-derived populations that have their territories guaranteed by the Brazilian Constitution. The present study investigated the hemoglobin (Hb) variants among these population groups. This study was conducted in a total of 2843 individuals of Brazilian Quilombola communities of the Bahia, Pará, and Piauí states. All the participants had their Hb profiles evaluated. The Hb S (HBB: c.20A>T) variant was described in all the studied localities. However, the individuals in Bahia State had the highest frequency of the Hb C (HBB: c.19G>A) variant; individuals from Piauí State had a higher frequency of the Hb D-Punjab (HBB: c.364G>C) variant compared to the other states, and individuals from Pará State only carried the Hb S variant. The present study revealed a specific distribution of Hb variants that could represent different waves of African influence in these Brazilian populations.


Assuntos
Frequência do Gene , Hemoglobina Falciforme/genética , Hemoglobinas Anormais/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Brasil , Criança , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
5.
Sci Rep ; 9(1): 14829, 2019 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-31616024

RESUMO

Sickle cell anemia (SCA) is a hemolytic disease in which vaso-occlusion is an important pathophysiological mechanism. The treatment is based on hydroxyurea (HU), which decreases leukocyte counts and increases fetal hemoglobin synthesis. Different cell types are thought to contribute to vaso-occlusion. Nevertheless, the role of monocytes subsets remains unclear. We investigated frequencies of monocytes subsets in blood and their response to HU therapy, testing their ability to express pro-inflammatory molecules and tissue factor (TF). We identified major changes in monocyte subsets, with classical monocytes (CD14++CD16-) appearing highly frequent in who were not taking HU, whereas those with patrolling phenotype (CD14dimCD16+) were enriched in individuals undergoing therapy. Additionally, HU decreased the production of TNF-α, IL1-ß, IL-6, IL-8 as well as TF by the LPS-activated monocytes. Likewise, frequency of TF-expressing monocytes is increased in patients with previous vaso-occlusion. Moreover, activated monocytes expressing TF produced several pro-inflammatory cytokines simultaneously. Such polyfunctional capacity was dramatically dampened by HU therapy. The frequency of classical monocytes subset was positively correlated with percentage cytokine producing cells upon LPS stimulation. These findings suggest that classical monocytes are the subset responsible for multiple pro-inflammatory cytokine production and possibly drive inflammation and vaso-occlusion in SCA which is damped by HU.


Assuntos
Anemia Falciforme/tratamento farmacológico , Hidroxiureia/farmacologia , Mediadores da Inflamação/metabolismo , Monócitos/efeitos dos fármacos , Adolescente , Anemia Falciforme/sangue , Anemia Falciforme/imunologia , Criança , Feminino , Humanos , Hidroxiureia/uso terapêutico , Contagem de Leucócitos , Masculino , Monócitos/imunologia , Monócitos/metabolismo
6.
Transplantation ; 86(11): 1628-30, 2008 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-19077901

RESUMO

Preservation of ovarian functions in woman with premature ovarian failure remains an issue in reproductive medicine. Hormone replacement therapy for maintaining endocrine functions, and cryopreservation of embryos or oocytes for those who wish pregnancy, are some of the choices. However, ovarian transplantation is a more physiological alternative, although problems related to ovarian ischemia have been reported. Herein, we investigated the viability of autologous transplantation of the ovarian tissue into the rat peritoneum, without vascular reanastomosis. Twenty animals in the study group had both ovaries excised, and each ovary was dissected into two halves. A half of an ovary was autotransplanted to the peritoneal surface, closely located to the left epigastric vessels. This simple procedure does not require surgical vascular reanastomosis while it maintains appropriate follicular growth and therefore should be further considered as an alternative for women undergoing oophorectomy, not only to maintain endocrine functions but also for fertility preservation.


Assuntos
Ovário/transplante , Insuficiência Ovariana Primária/terapia , Transplante/métodos , Animais , Criopreservação , Feminino , Fertilidade , Sobrevivência de Enxerto , Oócitos/metabolismo , Ovariectomia , Ovário/fisiologia , Ratos , Análise de Regressão , Transplante Autólogo , Resultado do Tratamento
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA