Browsing by Author "Ferreira, Rita"
Now showing 1 - 5 of 5
Results Per Page
Sort Options
- Cell-to-cell transmission of HIV-1 and HIV-2 from infected macrophages and dendritic cells to CD4+ T lymphocytesPublication . Calado, Marta; Pires, David; Conceição, Carolina; Ferreira, Rita; Santos-Costa, Quirina; Anes, Elsa; Azevedo-Pereira, José MiguelMacrophages (Mø) and dendritic cells (DCs) are key players in human immunodeficiency virus (HIV) infection and pathogenesis. They are essential for the spread of HIV to CD4+ T lymphocytes (TCD4+) during acute infection. In addition, they constitute a persistently infected reservoir in which viral production is maintained for long periods of time during chronic infection. Defining how HIV interacts with these cells remains a critical area of research to elucidate the pathogenic mechanisms of acute spread and sustained chronic infection and transmission. To address this issue, we analyzed a panel of phenotypically distinct HIV-1 and HIV-2 primary isolates for the efficiency with which they are transferred from infected DCs or Mø to TCD4+. Our results show that infected Mø and DCs spread the virus to TCD4+ via cell-free viral particles in addition to other alternative pathways. We demonstrate that the production of infectious viral particles is induced by the co-culture of different cell populations, indicating that the contribution of cell signaling driven by cell-to-cell contact is a trigger for viral replication. The results obtained do not correlate with the phenotypic characteristics of the HIV isolates, namely their co-receptor usage, nor do we find significant differences between HIV-1 and HIV-2 in terms of cis- or trans-infection. The data presented here may help to further elucidate the cell-to-cell spread of HIV and its importance in HIV pathogenesis. Ultimately, this knowledge is critical for new therapeutic and vaccine approaches.
- Comparison of milk from two different cow breeds Barrosã and FrísiaPublication . Pires, Preciosa; Fernandes, Élia; Vilarinho, Manuela; Barros, Mário; Ferreira, Rita; Carneiro, Luísa; Almeida, Gonçalo; Vaz-Velho, ManuelaMilk from two different cow breeds, Barrosã and Frísia, was studied. Within the same breed five and four milk samples were taken respectively for chemical and microbiological analysis. The following chemical parameters were analysed in triplicate: Total Fat, Fatty Acids Identification and Quantification, Protein, Casein, Albumin, Non-protein Nitrogen, Vitamin A, Vitamin D, Phosphorus, Potassium, Sodium, Iron, Magnesium, Calcium, Ash, Total solids, Lactic acid and Acidity. In general terms milk from Barrosã breed showed higher values for all analysed parameters except for Total Fat, Total Solids and Vitamin D. Statistical analysis, by testing the chemical parameters all together using the Hotelling T2 test showed that milk samples from the two cow breeds were significantly different (α=0,05). Microbiological analysis (Total Viable Counts (30ºC), Escherichia coli, Staphylococcus coagulase + and Listeria monocytogenes) was also performed. Staphylococcus coagulase + was found in one milk sample from Barrosã breed. Listeria monocytogenes was found in two milk samples from Frísia breed.
- A marca Oliveira da Serra na novela Laços de Sangue: um caso de brand placementPublication . Ferreira, RitaO Brand Placement na ficção audiovisual apresenta-se, para as marcas, como uma alternativa à publicidade clássica e linear sujeita à saturação publicitária e à fragmentação da audiência, utilizando estruturas de construção de significado cada vez mais complexas. O presente estudo analisa o Brand Placement da marca “Oliveira da Serra" na novela “Laços de Sangue”, em 43 episódios. Na primeira parte, define-se as perguntas de partida, os objetivos da investigação e a metodologia utilizada. De seguida, apresenta-se o enquadramento teórico sobre Telenovela, Marketainment e Brand Placement. Na segunda parte, apresenta-se a análise empírica, onde se descreve os tipos de Placement identificados na novela - Anúncio Publicitário, Separador “Alentejo”, Inserções sem produto e Inserções com produto - e as relações estabelecidas entre eles; as variáveis de Troup (1991) utilizadas na análise de 12 inserções, 6 com produto e 6 sem produto, escolhidas aleatoriamente; e as conclusões. Finalmente, apresenta-se a análise efetuada a cada inserção, os quadros de quantificação e relação, as fichas de personagens e cenários.
- Stress response of lactobacillus delbrueckii ssp. bulgaricus: the importance of the growth pHPublication . Silva, Joana; Carvalho, Ana Sofia; Ferreira, Rita; Teixeira, Paula; Gibbs, PaulThe degree of thermotolerance conferred on Lactobacillus delbrueckii ssp. bulgaricus, by an acid shock or a heat shock, when cells were grown in controlled and non-controlled pH conditions, during exponential and stationary growth phases, was evaluated. For exponential phase cells, thermotolerance was enhanced by submitting the cells to prior heat or acid shocks independently of the pH of growth conditions. Stationary phase cells were significantly more resistant to heating than cells in the exponential phase but only when growth occurred under non-controlled pH. Induced thermotolerance in stationary phase cells, was only observed for cells grown under controlled pH. Except for cells in the stationary growth phase grown under non-controlled pH, the heat or acid shock treatments resulted in an intracellular increase in the well - known heat shock proteins, GroES and GroEL. The presence of chloramphenicol negated the heat shock response and production of GroES and GroEL, confirming that de novo protein synthesis was involved in cell protection. These proteins were also identified in stationary phase cells grown under non-controlled pH, suggesting their involvement in induced thermotolerance during growth at low pH. Very few studies have investigated the response of stationary phase cells. The evaluation development of the response to sub-lethal stresses as a function of the pH conditions during growth is a new insight;. In fact, it was demonstrated that the pH of growth is a crucial factor.
- Unravelling the triad of neuroinvasion, neurodissemination, and neuroinflammation of human immunodeficiency virus type 1 in the central nervous systemPublication . Calado, Marta; Ferreira, Rita; Pires, David; Santos-Costa, Quirina; Anes, Elsa; Brites, Dora; Azevedo-Pereira, José MiguelSince the identification of human immunodeficiency virus type 1 (HIV-1) in 1983, many improvements have been made to control viral replication in the peripheral blood and to treat opportunistic infections. This has increased life expectancy but also the incidence of age-related central nervous system (CNS) disorders and HIV-associated neurodegeneration/neurocognitive impairment and depression collectively referred to as HIV-associated neurocognitive disorders (HAND). HAND encompasses a spectrum of different clinical presentations ranging from milder forms such as asymptomatic neurocognitive impairment or mild neurocognitive disorder to a severe HIV-associated dementia (HAD). Although control of viral replication and suppression of plasma viral load with combination antiretroviral therapy has reduced the incidence of HAD, it has not reversed milder forms of HAND. The objective of this review, is to describe the mechanisms by which HIV-1 invades and disseminates in the CNS, a crucial event leading to HAND. The review will present the evidence that underlies the relationship between HIV infection and HAND. Additionally, recent findings explaining the role of neuroinflammation in the pathogenesis of HAND will be discussed, along with prospects for treatment and control.