Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 15 de 15
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Vaccine ; 40(35): 5189-5196, 2022 08 19.
Artigo em Inglês | MEDLINE | ID: mdl-35907676

RESUMO

BACKGROUND: Vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has proven to be a successful strategy for prevent severe infections. CoronaVac and BNT162b2 are the most used vaccines worldwide, but their use in heterologous vaccination schedules is still subjected to evaluation. METHODS: Fifty healthy individuals who received heterologous prime-boost vaccination with CoronaVac and BNT162b2 were enrolled in a post-vaccination serological follow-up longitudinal prospective study. We evaluated specific serum anti-receptor binding domain (RBD) IgG antibody levels, and their capacity to block RBD-ACE2 interaction with a surrogate neutralization assay. In 20 participants, we assessed antibody binding kinetics by surface plasmon resonance, and Fc-mediated functions by ADCC and ADCP reporter assays. RESULTS: Our baseline seronegative cohort, displayed seroconversion after two doses of CoronaVac and an important decrease in serum anti-RBD IgG antibodies levels 80 days post-second dose. These levels increased significantly early after the third dose with BNT162b2, but 73 days after the booster we found a new fall. Immunoglobulin functionalities showed a similar behavior. CONCLUSIONS: The heterologous prime-boost vaccination with CoronaVac and BNT162b2 generated an impressive increase in serum anti-RBD specific antibody levels followed by a drop. Nevertheless, these titers remained well above those found in individuals only vaccinated with CoronaVac in the same elapsed time. Serum IgG levels showed high correlation with antibody binding analysis, their capacity to block RBD-ACE2 interaction, and Fc-effectors mechanisms. Our work sheds light on the humoral immune response to heterologous vaccination with CoronaVac and BNT162b2, to define a post-vaccination correlate of protection against SARS-CoV-2 infection and to discuss the scheduling of future vaccine boosters in general population.


Assuntos
COVID-19 , Vacinas Virais , Enzima de Conversão de Angiotensina 2 , Anticorpos Antivirais , Vacina BNT162 , COVID-19/prevenção & controle , Vacinas contra COVID-19 , Humanos , Imunidade Humoral , Imunoglobulina G , Estudos Prospectivos , SARS-CoV-2 , Vacinação
2.
PLoS One ; 17(7): e0271671, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35867649

RESUMO

The retropepsin (PR) of the Bovine leukemia virus (BLV) plays, as in other retroviruses, a crucial role in the transition from the non-infective viral particle to the infective virion by processing the polyprotein Gag. PR is expressed as an immature precursor associated with Gag, after an occasional -1 ribosomal frameshifting event. Self-hydrolysis of PR at specific N- and C-terminal sites releases the monomer that dimerizes giving rise to the active protease. We designed a strategy to express BLV PR in E. coli as a fusion protein with maltose binding protein, with a six-histidine tag at its N-terminal end, and bearing a tobacco etch virus protease hydrolysis site. This allowed us to obtain soluble and mature recombinant PR in relatively good yields, with exactly the same amino acid composition as the native protein. As PR presents relative promiscuity for the hydrolysis sites we designed four fluorogenic peptide substrates based on Förster resonance energy transfer (FRET) in order to characterize the activity of the recombinant enzyme. These substrates opened the way to perform kinetic studies, allowing us to characterize the dimer-monomer equilibrium. Furthermore, we obtained kinetic evidence for the existence of a conformational change that enables the interaction with the substrate. These results constitute a starting point for the elucidation of the kinetic properties of BLV-PR, and may be relevant not only to improve the chemical warfare against this virus but also to better understand other viral PRs.


Assuntos
Ácido Aspártico Proteases , Vírus da Leucemia Bovina , Dimerização , Escherichia coli/genética , Escherichia coli/metabolismo , Protease de HIV/metabolismo , Cinética , Vírus da Leucemia Bovina/genética , Vírus da Leucemia Bovina/metabolismo , Peptídeo Hidrolases/metabolismo
4.
Clin Kidney J ; 15(3): 527-533, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-35198159

RESUMO

BACKGROUND: Antibody response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) after mRNA or adenoviral vector-based vaccines is weak in kidney transplant (KT) patients. However, few studies have focused on humoral response after inactivated virus-based vaccines in KT. Here, we compare antibody response following vaccination with inactivated virus (CoronaVac®) and BNT162b2 mRNA. METHODS: A national multicentre cross-sectional study was conducted. The study group was composed of patients from all KT centres in Uruguay, vaccinated between 1 and 31 May 2021 (CoronaVac®, n = 245 and BNT162b2, n = 39). The control group was constituted of 82 healthy individuals. Participants had no prior confirmed coronavirus disease 2019 (COVID-19) test. Blood samples were collected between 30 and 40 days after the second dose. Serum-specific immunoglobulin G (IgG) antibodies against the receptor-binding domain (RBD) of SARS-CoV-2 Spike protein were determined using the COVID-19 IgG QUANT ELISA Kit. RESULTS: Only 29% of KT recipients showed seroconversion (36.5% BNT162b2, 27.8% inactivated virus, P = 0.248) in comparison with 100% in healthy control with either vaccine. Antibody levels against RBD were higher with BNT162b mRNA than with inactivated virus [median (interquartile range) 173 (73-554) and 29 (11-70) binding antibody units (BAU)/mL, P < 0.034] in KT and 10 times lower than healthy control [inactivated virus: 308 (209-335) and BNT162b2: 2638 (2608-3808) BAU/mL, P < 0.034]. In multivariate analysis, variables associated with negative humoral response were age, triple immunosuppression, estimated glomerular filtration rate and time post-KT. CONCLUSION: Seroconversion was low in KT patients after vaccination with both platforms. Antibody levels against SARS-CoV-2 were lower with inactivated virus than BNT162b mRNA. These findings support the need for strategies to improve immunogenicity in KT recipients after two doses of either vaccine.

6.
Financ Res Lett ; 38: 101851, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36569648

RESUMO

Using the multifractional Brownian motion as a model of the price dynamics, we analyze the impact of the COVID-19 pandemic on the efficiency of fifteen financial markets from Europe, US and Asia. We find that Asian markets (Hang Seng, Nikkei 225, Kospi) have recovered full efficiency, while European and US markets - after an initial rebound - have not yet returned to the pre-crisis level of efficiency. The inefficiency that currently characterizes US and European markets originates moderately high levels of volatility.

7.
Chaos ; 28(3): 031102, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29604638

RESUMO

We combine two existing estimators of the local Hurst exponent to improve both the goodness of fit and the computational speed of the algorithm. An application with simulated time series is implemented, and a Monte Carlo simulation is performed to provide evidence of the improvement.

8.
Chaos ; 27(7): 071102, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28764403

RESUMO

The last systemic financial crisis has reawakened the debate on the efficient nature of financial markets, traditionally described as semimartingales. The standard approaches to endow the general notion of efficiency of an empirical content turned out to be somewhat inconclusive and misleading. We propose a topological-based approach to quantify the informational efficiency of a financial time series. The idea is to measure the efficiency by means of the pointwise regularity of a (stochastic) function, given that the signature of a martingale is that its pointwise regularity equals 12. We provide estimates for real financial time series and investigate their (in)efficient behavior by comparing three main stock indexes.

9.
Vet Res ; 44: 19, 2013 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-23506507

RESUMO

It is widely accepted that the majority of cancers result from multiple cellular events leading to malignancy after a prolonged period of clinical latency, and that the immune system plays a critical role in the control of cancer progression. Bovine leukemia virus (BLV) is an oncogenic member of the Retroviridae family. Complete genomic sequences of BLV strains isolated from peripheral blood mononuclear cells (PBMC) from cattle have been previously reported. However, a detailed characterization of the complete genome of BLV strains directly isolated from bovine tumors is much needed in order to contribute to the understanding of the mechanisms of leukemogenesis induced by BLV in cattle. In this study, we performed a molecular characterization of BLV complete genomes from bovine B-cell lymphosarcoma isolates. A nucleotide substitution was found in the glucocorticoid response element (GRE) site of the 5' long terminal repeat (5'LTR) of the BLV isolates. All amino acid substitutions in Tax previously found to be related to stimulate high transcriptional activity of 5'LTR were not found in these studies. Amino acid substitutions were found in the nucleocapsid, gp51 and G4 proteins. Premature stop-codons in R3 were observed. Few mutations or amino acid substitutions may be needed to allow BLV provirus to achieve silencing. Substitutions that favor suppression of viral expression in malignant B cells might be a strategy to circumvent effective immune attack.


Assuntos
Leucose Enzoótica Bovina/virologia , Genoma Viral , Vírus da Leucemia Bovina/genética , Linfoma de Células B/veterinária , Sequência de Aminoácidos , Animais , Sequência de Bases , Bovinos , Vírus da Leucemia Bovina/química , Vírus da Leucemia Bovina/metabolismo , Linfoma de Células B/virologia , Dados de Sequência Molecular , Reação em Cadeia da Polimerase/veterinária , Alinhamento de Sequência/veterinária
10.
Br J Haematol ; 157(6): 709-17, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22489537

RESUMO

As an approach to determining the aetiology of chronic lymphocytic leukaemia (CLL), we searched for a virus expressed in human CLL B-cells by combining high-throughput sequencing and digital subtraction. Pooled B-cell mRNA transcriptomes from five CLL patients and five healthy donors were sequenced with 454 Life Sciences technology. Human reads were excluded by BLAST (Basic Local Alignment Search Tool) and BLAT (BLAST-like alignment tool) searches. Remaining reads were screened with BLAST against viral databases. Purified B-cells from two CLL patients, with and without stimulation by phorbol-esters, were sequenced using Illumina technology to achieve depth of sequencing. Burrows-Wheeler Aligner mapping and BLAST searches were used for the Illumina data. Pyrosequencing resulted in about 400 000 reads per sample. No viral candidate could be found. Illumina single-end sequencing for 115 cycles yielded an average of 26 ± 2·5 million filtered reads per sample, of which 2·2 ± 0·6 million remained unmapped to human references. BLAST searches of these reads against viral and human databases assigned nine reads to an Epstein-Barr virus origin, in one sample following phorbol-ester stimulation. Other reads showing a putative viral origin were dismissed after further analysis. Despite an in-depth analysis of the CLL transcriptome reaching more than 100 million sequences, we have not found evidence for a putative viral candidate in CLL.


Assuntos
Linfócitos B/virologia , Leucemia Linfocítica Crônica de Células B/genética , Leucemia Linfocítica Crônica de Células B/virologia , Transcriptoma , Idoso , Linfócitos B/metabolismo , Feminino , Humanos , Leucemia Linfocítica Crônica de Células B/metabolismo , Masculino , Pessoa de Meia-Idade
11.
Br J Nutr ; 106 Suppl 1: S191-3, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22005426

RESUMO

Urolithiasis is a common clinical problem in dogs. Struvite and calcium oxalate are the predominant mineral types in dog urolithiasis. The aim of the present study was to compare the effect of two commercial dry foods formulated for the management of struvite urolithiasis with different anion-cation balance on urinary pH. For the trial, twelve privately owned adult dogs showing struvite urolithiasis were studied. The dogs were randomly divided into two groups (A and B) and fed two dissolving diets for 3 months. The analyses of urine were repeated six times. In both diets, the anion-cation balance was negative ( - 203 and - 192 for diets A and B, respectively). At the first urine analysis, pH values of all the dogs were close to 8.0, and bacteria were present in about 70 % of the samples and thus an antimicrobial was administered for 1 week. Both groups showed a progressive decrease in pH values, and after 2 months, in both cases, the recommended pH values for stone dissolution were achieved. From the sampling at 30 d, group A showed pH values significantly (P < 0.05) lower than group B, probably due to the lower anion-cation balance of diet A. The combination of antimicrobial and dietary therapy allowed the dissolution of struvite uroliths in both groups, even if the utilisation of the diet characterised by the lower anion-cation balance seems to decrease the urinary pH more rapidly. In this case, it seems necessary to interrupt the dietary treatment in order to avoid the risk of other diseases.


Assuntos
Ração Animal/análise , Doenças do Cão/dietoterapia , Compostos de Magnésio/química , Fosfatos/química , Urolitíase/veterinária , Fenômenos Fisiológicos da Nutrição Animal , Animais , Antibacterianos/uso terapêutico , Dieta/veterinária , Doenças do Cão/tratamento farmacológico , Doenças do Cão/urina , Cães , Fluoroquinolonas/uso terapêutico , Concentração de Íons de Hidrogênio , Estruvita , Infecções Urinárias/tratamento farmacológico , Infecções Urinárias/veterinária , Urolitíase/dietoterapia , Urolitíase/urina
13.
In. Boggia, José; López, Alejandra; Bianchi, Sergio; Noboa, Oscar; Gadola, Liliana; Briva, Arturo; Hurtado, Javier; Grignola, Juan Carlos; Rodríguez, MaríaJosé. Fisiopatología: mecanismos de las disfunciones orgánicas. Montevideo, Oficina del Libro FEFMUR, 2a. ed; 2011. p.53-102.
Monografia em Espanhol | LILACS | ID: lil-759797
14.
Leuk Lymphoma ; 51(11): 2070-8, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20929321

RESUMO

B-cell chronic lymphocytic leukemia (CLL) is characterized by the accumulation of long-lived circulating clonal leukemic B-cells, although the etiopathogenesis remains unclear. The incidence of CLL is variable in different regions around the world. While it is the most frequent chronic leukemia in Western countries, it has a low incidence in Asia. In this work we have investigated the immunoglobulin heavy chain gene rearrangements and mutational status in 80 Uruguayan patients with CLL, and compared these results with those obtained in other geographic regions. Our results demonstrate that Uruguayan patients with CLL display an IGHV gene usage which resembles that observed in Mediterranean countries and exhibits certain differences compared with Brazilian and Asian series, as expected, considering the ethnic basis of the Uruguayan population. This suggests that genetic influences could be important in the development and etiopathogenesis of CLL, but larger studies are necessary to substantiate this possibility.


Assuntos
Rearranjo Gênico de Cadeia Pesada de Linfócito B , Genes de Cadeia Pesada de Imunoglobulina , Região Variável de Imunoglobulina/genética , Leucemia Linfocítica Crônica de Células B/genética , Mutação , Adulto , Idoso , Análise Mutacional de DNA , Feminino , Frequência do Gene , Geografia , Humanos , Leucemia Linfocítica Crônica de Células B/imunologia , Masculino , Pessoa de Meia-Idade , Filogenia , Uruguai
15.
Arch Virol ; 155(4): 481-9, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20169372

RESUMO

Bovine leukaemia virus (BLV) is an oncogenic member of the genus Deltaretrovirus of the family Retroviridae. Recent studies revealed that BLV strains can be classified into six different genotypes and raised the possibility that another genotype may exist. In order to gain insight into the degree of genetic variability of BLV strains circulating in the South American region, a phylogenetic analysis was performed using gp51 env gene sequences. The results of these studies revealed the presence of seven BLV genotypes in this geographic region and the suitability of partial gp51 env gene sequences for phylogenetic inference. A significant number of amino acid substitutions found in BLV strains isolated in South America map to the second neutralization domain of gp51. A 3D molecular model of BLV gp51 revealed that these substitutions are located on the surface of the molecule. This may provide a selective advantage to overcome immune host neutralization.


Assuntos
Leucose Enzoótica Bovina/virologia , Vírus da Leucemia Bovina/classificação , Vírus da Leucemia Bovina/isolamento & purificação , Polimorfismo Genético , Sequência de Aminoácidos , Substituição de Aminoácidos/genética , Animais , Bovinos , Análise por Conglomerados , Epitopos/genética , Produtos do Gene env/genética , Genótipo , Vírus da Leucemia Bovina/genética , Modelos Moleculares , Dados de Sequência Molecular , Filogenia , Estrutura Terciária de Proteína , Alinhamento de Sequência , Análise de Sequência de DNA , Homologia de Sequência , América do Sul
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...