Regulation and role of IL-7 production in HIV-1 infection

The concentration of interleukin-7 (IL-7) in human serum is elevated in various clinical conditions associated with lymphopenia, including HIV-1 infection. IL-7 is an essential factor for T cell differentiation and survival, and it was suggested that high serum IL-7 concentration may represent a homeostatic response to T cell depletion, which may promote T cell regeneration. In order to increase our understanding on the regulation of IL-7 production, we investigated specimens from HIV-1 infected patients during chronic infection and in long term non-progressors (LTNPs). Serum IL-7 levels correlated with T-cell depletion in HIV-1 infected individuals. In some patients, we observed that serum IL-7 decreased upon progression to AIDS, suggesting a role for IL-7 in T-cell maintenance in sporadic cases. Interestingly, IL-7 levels were significantly lower in stable LTNPs than in patients who lost the LTNP status in a 3-year follow-up (P<0.001), indicating that serum IL-7 concentration might be a valuable marker for maintenance of the LTNP status. The number of CD8+CD28- T cells increases significantly during aging and during HIV-1 infection. These cells have a reduced expression of the IL-7 receptor alpha (IL-7Rα), as compared to CD8+CD28+ T cells. As CD8+CD28- T cells have been associated with dendritic and T cell suppression, we analyzed whether an increase in CD8+CD28- T cell numbers during HIV-1 infection could lead to impaired T cell responses. Peripheral blood CD8+CD28- T cells of both HIV-infected and non-infected individuals promoted dendritic cell activation. The CD8+CD28- T cell accumulation during HIV-1 infection may thus contribute to inflammatory reactions and immune activation. Stromal cells and intestinal epithelial cells are known to produce IL-7. The mechanisms and cellular factors regulating IL-7 production are still unclear. We assessed whether IL-1β and IFN-γ, cytokines produced during inflammatory conditions, may impact on IL-7 production. We used human intestinal epithelial cells (DLD-1 cell line) and bone marrow stromal cells (HS27 cell line) to evaluate IL-7 production at the mRNA and protein levels. To assess whether treatment of HS27 cells with IL-1β and/or IFN-γ leads to changes in the gene expression of cytokines, Toll-like receptors (TLRs) and chemokines, we analysed gene expression profiles using the whole-genome microarray Human Gene 1.0 ST. We found that IFN-γ enhanced the expression of IL-7 protein and mRNA (P<0.001) in both cell lines. IL-1β treatment led to a significant down-regulation (P<0.001) of IL-7 mRNA expression in both cell lines. The gene profiles revealed dramatic changes in expression of cytokines and their receptors, of IFN regulatory factors (IRF-1 and 2) and of important chemo-attractants for T cells. The microarray results were verified by additional methods. Our results were discussed in the setting of inflammation and T-cell survival in the gut compartment during HIV-1 infection where stromal and epithelial cells may produce factors that contribute to impaired IL-7 homeostasis and homing of T cells. It was previously reported that IL-7 might stimulate T cell activation and CD95 mediated T cell apoptosis. HIV-1 infection leads to B cell abnormalities including increased apoptosis via the CD95 death receptor pathway and loss of memory B cells. Here we present a novel mechanism that can lead to increased B cell apoptosis in the presence of high IL-7 concentration. T cells cultured with IL-7 induced high CD95 expression on resting B cells together with an increased sensitivity to CD95 mediated apoptosis. As the mediator molecule responsible for B cell priming to CD95 mediated apoptosis we identified the cytokine IFN-γ that T cells secreted in response to IL-7. In the serum of HIV-1 infected individuals IL-7 and IFN-γ levels were in correlation and the level of both cytokines correlated with CD95 expression on circulating B lymphocytes in non-viremic individuals. These results indicate a potential link between IL-7 and the increased B cell apoptosis observed in HIV-1 infected individuals. In conclusion the results presented in this PhD thesis highlight mechanisms of regulation of IL-7 production dependent on the number of circulating T cells and on the exposure of IL-7 producing cells to high levels of inflammatory cytokines. We also present data on the role of IL-7 in regulating CD95 expression and CD95 mediated apoptosis on B cells through IFN-γ produced by T cells; the impact of this finding on the outcome of IL-7 therapy during HIV-1 infection will be verified by ongoing clinical studies

The Impact of Inflammation and Immune Activation on B Cell Differentiation during HIV-1 Infection

One important pathogenic feature of human immunodeficiency virus (HIV)-1 infection is chronic immune activation and impaired survival of T and B cells. A decline of resting memory B cells was reported to occur in both children and adults infected with HIV-1; these cells are responsible for maintaining an adequate serological response to antigens previously encountered in life through natural infection or vaccination. Further understanding of the mechanisms leading to impaired B cell differentiation and germinal center reaction might be essential to design new HIV vaccines and therapies that could improve humoral immune responses in HIV-1 infected individuals. In the present article we summarize the literature and present our view on critical mechanisms of B cell development impaired during HIV-1 infection. We also discuss the impact of microbial translocation, a driving force for persistent inflammation during HIV-1 infection, on survival of terminally differentiated B cells and how the altered expression of cytokines/chemokines pivotal for communication between T and B cells in lymphoid tissues may impair formation of memory B cells

Structure and Magnetic Properties of PZT/CoCr Heterostructures

The microstructure, crystallographic structure and magnetic properties of ferroelectric-ferromagnetic PZT/CoCr heterostructures have been investigated by using XRD, SEM and VSM.~Upon applying an electric field, the in-plane magnetization of the heterostructures decreases at various bias magnetic fields. The change in magnetization and the magnetization reversed voltage were obtained. The results demonstrate that the change in magnetic anisotropy can be controlled by electric field via strain-mediated magnetoelectric coupling

Firm History and Managerial Entrenchment: Empirical Evidence for Vietnam Listed Firms

Managerial entrenchment occurs when managers are able to manipulate financing decisions to support their own interests rather than those of shareholders. Such possible actions can involve deception and fraud. Furthermore, the market timing activity is explained by managers' financing decisions through which companies choose to raise debt or equity to finance their investment opportunities. Nevertheless, the relationship between managerial entrenchment and leverage ratio, together with the link between market timing and leverage ratio, have not been considered carefully and investigated in the Vietnamese context. The paper provides empirical evidence of the effect of managerial entrenchment and market timing through firms' histories on leverage ratio in Vietnam using a sample of 289 non-financial firms listed on the Ho Chi Minh Stock Exchange (HOSE) during the period 2006-2017. OLS, GMM and the endogenous switching methods are used for estimating the models. Findings from the paper indicate that there is a negative relationship between managerial entrenchment and leverage ratio, and that there is a negative effect of firm history, including financial deficit, various timing measures, and stock price history on the leverage ratios of Vietnam's listed firms

The Temperature-sensitivity of a Critical Electric Field Induced Magnetic Easy-axis Reorientation Ferromagnetic/ferroelectric Layered Heterostructures

We have investigated the effects of temperature on the magnetic easy axis reorientation (EARs) in polycrystalline ferromagnetic (FM) nano-scale thin films, i.e. (001)-oriented cubic films such as Fe, Ni, CFO and (0001)-oriented hexagonal films such as Co, grown on ferroelectric (FE) substrates, for example PZT, BTO substrates. The model of FM/FE bilayered heterostructures has been applied to study the total free energy of the FM films. By minimizing this energy, we have shown that temperature has a significant effect on a critical electric field induced magnetic reorientation

Choosing the best machine tool in mechanical manufacturing

Machine tools are indispensable components and play an important role in mechanical manufacturing. The equipment of machine tools has a huge effect on the operational efficiency of businesses. Each machine tool type is described by many different criteria, such as cost, technological capabilities, accuracy, energy consumption, convenience in operation, safety for workers, working noise, etc. If the selection of machine is only based on one or several criteria, it will be really easy to make mistakes, which means it is not possible to choose the real best machine. A machine is considered to be the best only when it is chosen based on all of its criteria. This work is called multi-criteria decision-making (MCDM). In this study, the selection of machine tools has been done using two different multi-criteria decision-making methods, including the FUCA method (Faire Un Choix Adéquat) and the CURLI method (Collaborative Unbiased Rank List Intergration). These are two methods with very different characteristics. When using the FUCA method, it is necessary to normalize the data and determine the weights for the criteria. Meanwhile, if using the CURLI method, these two things are not necessary. The selection of these two distinct methods is intended to produce the most generalizable conclusions. Three types of machine tool, which are considered in this study, include grinding machine, drilling machine and milling machine. The number of grinders that were offered for selection was twelve, the number of drills that were surveyed in this study was thirteen, while nine were the number of milling machines that were given for selection. The objective of this study is to determine the best solution in each type of machine. The results of ranking the machines are very similar when using the two mentioned methods. Specially, in all the surveyed cases, the two methods FUCA and CURLI always find the same best alternative. Accordingly, it is possible to firmly come to a conclusion that the FUCA method and the CURLI method are equally effective in machine tool selection. In addition, this study has determined the best three machines corresponding to the three different machine type

Extent to which people perceive and accept Covid-19 vaccines in north central Vietnam

To achieve herd immunity against Covid-19, the willingness of residents to get vaccinated and successful vaccination policies go hand in hand. This paper aims to understand the perceptions, acceptance, hesitation, and refusal of Covid-19 vaccines in Nghe An, Vietnam. We used an online survey to collect data during March of 2021. The Bayesian regression model (BRM) was used to identify the factors affecting vaccination decisions. The empirical results show that respondents’ livelihoods were considerably affected by the Covid-19 pandemic, and there was a subtle difference in Covid-19 impacts on the lives of urban residents and their rural counterparts. In addition, respondents reported an overall positive attitude towards Covid-19 vaccination in which 84.28% were willing to get vaccinated, 14.85% were hesitant, and 0.87% refused vaccination. Their vaccination decisions were associated with vaccine side effects, information, income, job type, gender, and trust in government. Our findings offer policy implications for devising strategies for vaccine distribution in the study area and beyond

Heat Dissipation for Microprocessor Using Multiwalled Carbon Nanotubes Based Liquid

Carbon nanotubes (CNTs) are one of the most valuable materials with high thermal conductivity (2000 W/m·K compared with thermal conductivity of Ag 419 W/m·K). This suggested an approach in applying the CNTs in thermal dissipation system for high power electronic devices, such as computer processor and high brightness light emitting diode (HB-LED). In this work, multiwalled carbon nanotubes (MWCNTs) based liquid was made by COOH functionalized MWCNTs dispersed in distilled water with concentration in the range between 0.2 and 1.2 gram/liter. MWCNT based liquid was used in liquid cooling system to enhance thermal dissipation for computer processor. By using distilled water in liquid cooling system, CPU’s temperature decreases by about 10°C compared with using fan cooling system. By using MWCNT liquid with concentration of 1 gram/liter MWCNTs, the CPU’s temperature decreases by 7°C compared with using distilled water in cooling system. Theoretically, we also showed that the presence of MWCNTs reduced thermal resistance and increased the thermal conductivity of liquid cooling system. The results have confirmed the advantages of the MWCNTs for thermal dissipation systems for the μ-processor and other high power electronic devices

Using metagenomics tool to evaluate the enrichment efficiency of methanogens in marine sediment in Truong Sa archipelage, Khanh Hoa province, Vietnam

Methanogens (archaea bacteria that produce methan) play an important role in the anaerobic digestion of organic waste, however, in marine environment, the low density of methanogens makes anaerobic digestion very slow. In this study, we used methagenomics tool to evaluate the enrichment efficiency of methanogens communities in marine sediments as a basis for building a anaerobic microbial formulation to treat organic waste in marine environment. The results of determination of methanogen density by MPN method have shown that methanogen has been accumulated with higher density (up to 3.2.107 MNP/ml) through 2 times of enrichment in artificial seawater with CH3COONa 10 mM substrate. In addition, metagenomics data have also shown a decrease in the number of archaea species through each enrichment, indicating that methanogenic species have gradually dominated the microbial community. This is the first study on using metagnenomics tools to evaluate the enrichment of methanogens in marine sediment samples in Truong Sa archipelago, Vietnam. Metagenomics data help provide more reliable evidence in microbial studies, especially in obligate anaerobes such as methanogens