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Showing 211 to 218 of 218 (0.02 seconds)| 211 |
Antikroppsnivåer efter insjuknande i Covid-19: Hur länge har man antikroppar och minnes-celler efter en avklarad Covid-19-infektion?Hedar, Rula January 2022 (has links)
IntroductionSars-CoV-2 (severe acute respiratory syndrome coronavirus-2) is an RNA virus that causes Covid-19 disease. This disease started in the city of Wuhan in China. This is not the first time that the coronavirus has caused an outbreak, in the last twenty years the coronavirus SARS-CoV (Severe Acute Respiratory Syndrome coronavirus) and MERSCoV (Middle East Respiratory Syndrome coronavirus) have caused two major outbreaks. The main structure of SARS-CoV-2 is built from membrane (M), envelope (E), nucleocapsid (N) and spike (S). When the body is infected by the virus, the virus enters the host cells by binding to the ACE2 receptor. Once the virus has entered the cell, it releases viral RNA. The virus's particles multiply inside the cell. New virus particles from the infected cell are produced, which in its turn infect new cells. The immune system against SARS-CoV-2 involves both the cellular and humoral arms, with neutralizing antibodies directed primarily against the S antigen.ObjectivesThis research aimed to study the litteratur describing how long the antibodies and memory cells remain in the blood, and how long the protection against the virus lasts.MethodThis work was based on six scientific articles to answer the question: How long protective antibody levels last in the plasma after resolution of a Covid-19 infection? To answer the question, the levels of the antibodies of different classes, IgG, IgM and IgA, against the receptorbinding domain (RBD)/ S, N protein were analysed as reported in litterature, as well as the reported amounts of T memory cells and B memory cells.ResultsHumans produce SARS-CoV-2-specific antibodies, especially IgM and IgG antibodies, and T cells response to SARS-CoV-2 infection. IgG and IgM antibody levels were higher in patients whith severe Covid-19 than in mild cases. Studies cohort included patients from 18 to 90 years old. The studies lasted on from three months and up to one year.
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ROLE OF FDCs AND FDC ACTIVATION IN PROMOTING HUMORAL IMMUNITY INCLUDING RESPONSES TO T-DEPENDENT ANTIGENS IN THE ABSENCE OF T CELLSEl, Sayed Rania 16 June 2009 (has links)
Follicular dendritic cells (FDCs) reside in primary B-cell follicles and in the light zones of germinal centers (GCs) in secondary follicles, where their dendrites interdigitate forming extensive networks intimately interacting with B-cells. In GCs, FDCs can be found at the edges attached to the supporting reticular fibers. They trap and arrange immune complexes (ICs) in vivo and in vitro in a periodic manner with 200–500Å spacing and provide both antigen-specific and non-specific accessory signals to B-cells. FDCs exist in resting and activated states, with two characteristically different phenotypes. In their activated state, FDCs upregulate the expression of accessory molecules and cytokines important in the FDC-B cell interaction in GCs. We sought to determine the mechanisms influencing the transition of FDCs from a resting to an activated state in GCs and their impact on T-cell dependent (TD) and independent (TI)-GC reactions (GCRs). We found that IC-FDC interactions via FDC-FcgammaRIIB induce the upregulation of FDC-FcgammaRIIB, -ICAM-1, and -VCAM-1, at both the protein and mRNA levels. We also reported for the first time the expression of TLR-4 on FDCs. Moreover, engagement of FDC-TLR4 with LPS activated NF-kappaB, up-regulated expression of important FDC-accessory molecules, including FcgammaRIIB, ICAM-1, and VCAM-1, and enhanced FDC accessory activity in promoting recall IgG responses. Moreover, IC-activated FDCs produced IL-6 and FDC-IL-6 promoted GCRs, somatic hypermutation (SHM) and IgG production. Further, we reported that binding of FDCs to collagen coated surfaces induced restoration of their dendritic processes and networks in vitro. In addition, we designed an FDC-supported in vitro model capable of induction and assessment of primary human antibody responses to protein antigens characterized by class-switching and affinity maturation. Uniquely, we generated TI immune responses to TD protein Ags in the complete absence of T cell help in vivo and in vitro. In the presence of FDC-associated second signals such as BAFF and C4BP, FDC- FcgammaRIIB-periodically trapped-ICs induced the production of Ag-specific IgM, GC-development and plasmablast-differentiation in anti-Thy-1-pretreated nude mice. Purified murine and human B cells cultured in vitro with IC-bearing FDCs also showed the production of antigen–specific IgM within just 48 h.
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"Resposta imune humoral na malária humana: quantidade e qualidade de anticorpos anti-Plasmodium falciparum" / Humoral immune response in human malaria : quantity and quality of anti-Plasmodium falciparum antibodiesLeoratti, Fabiana Maria de Souza 24 August 2004 (has links)
Neste estudo avaliamos a resposta imune humoral de indivíduos naturalmente expostos à malária em áreas endêmicas no Brasil. Os anticorpos IgG, IgG1, IgG2, IgG3, IgG4, IgM, IgE e IgA anti-formas eritrocitárias de Plasmodium falciparum foram determinadas por ELISA. Anticorpos IgG, IgG1, IgG2 de alta avidez e IgG3 de baixa avidez predominaram nos indivíduos sem complicações de malária ou assintomáticos, enquanto anticorpos IgG4, IgE e IgM predominaram nos indivíduos com complicações clínicas por malária. Os resultados mostram que mesmo em regiões com transmissão instável de malária pode ser observado o desenvolvimento de imunidade protetora quando anticorpos apropriados são produzidos / In this study, we have evaluated the humoral immune response of individuals naturally exposed to malaria living in endemic areas of Brazil. We determined IgG, IgG1, IgG2, IgG3, IgG4, IgM, IgE and IgA antibodies against Plasmodium falciparum blood stages by ELISA. We observed that the level of high avidity IgG, IgG1 and IgG2 and low avidity IgG3 antibodies were higher in asymptomatic individuals or with uncomplicated malaria, while IgG4, IgE and IgM antibodies were higher in individuals with complicated malaria. Taken together the results showed that even in unstable malaria regions it can be observed the development of protective immunity against malaria when appropriate antibodies are produced
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"Resposta imune humoral na malária humana: quantidade e qualidade de anticorpos anti-Plasmodium falciparum" / Humoral immune response in human malaria : quantity and quality of anti-Plasmodium falciparum antibodiesFabiana Maria de Souza Leoratti 24 August 2004 (has links)
Neste estudo avaliamos a resposta imune humoral de indivíduos naturalmente expostos à malária em áreas endêmicas no Brasil. Os anticorpos IgG, IgG1, IgG2, IgG3, IgG4, IgM, IgE e IgA anti-formas eritrocitárias de Plasmodium falciparum foram determinadas por ELISA. Anticorpos IgG, IgG1, IgG2 de alta avidez e IgG3 de baixa avidez predominaram nos indivíduos sem complicações de malária ou assintomáticos, enquanto anticorpos IgG4, IgE e IgM predominaram nos indivíduos com complicações clínicas por malária. Os resultados mostram que mesmo em regiões com transmissão instável de malária pode ser observado o desenvolvimento de imunidade protetora quando anticorpos apropriados são produzidos / In this study, we have evaluated the humoral immune response of individuals naturally exposed to malaria living in endemic areas of Brazil. We determined IgG, IgG1, IgG2, IgG3, IgG4, IgM, IgE and IgA antibodies against Plasmodium falciparum blood stages by ELISA. We observed that the level of high avidity IgG, IgG1 and IgG2 and low avidity IgG3 antibodies were higher in asymptomatic individuals or with uncomplicated malaria, while IgG4, IgE and IgM antibodies were higher in individuals with complicated malaria. Taken together the results showed that even in unstable malaria regions it can be observed the development of protective immunity against malaria when appropriate antibodies are produced
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NeurotoxinsKostrzewa, Richard M. 01 January 2016 (has links)
The era of selective neurotoxins arose predominately in the 1960s with the discovery of the norepinephrine (NE) isomer 6-hydroxydopamine (6-OHDA), which selectively destroyed noradrenergic sympathetic nerves in rats. A series of similarly selective neurotoxins were later discovered, having high affinity for the transporter site on nerves and thus being accumulated and able to disrupt vital intraneuronal processes, to lead to cell death. The Trojan Horse botulinum neurotoxins (BoNT) and tetanus toxin bind to glycoproteins on the neuronal plasma membrane, then these stealth neurotoxins are taken inside respective cholinergic or glycinergic nerves, producing months-long functional inactivation but without overtly destroying those nerves. The mitochondrial complex I inhibitor rotenone, while lacking total specificity, still destroys dopaminergic nerves with some selectivity; and importantly, results in the neural accumulation of synuclein-to model Parkinson’s disease (PD) in animals. Other neurotoxins target specific subtypes of glutamate receptors and produce excitotoxicity in nerves with that receptor population. The dopamine D2 receptor agonist quinpirole, termed a selective neurotoxin, produces a behavioral state replicating some of the notable features of schizophrenia, but without overtly destroying nerves. These processes, mechanisms or treatment-outcomes account for the means by which neurotoxins are classified as such, and represent some of the means by which neurotoxins as a group are able to destroy or functionally inactivate nerves; or replicate an altered neurological state. Selective neurotoxins have proven to be important in gaining insight into biochemical processes and mechanisms responsible for survival or demise of a nerve. Selective neurotoxins are useful also for animal modeling of human neural disorders such as PD, Alzheimer disease, attention-deficit hyperactivity disorder (ADHD), Lesch-Nyhan disease, tardive dyskinesia, schizophrenia and others. The importance of neurotoxins in neuroscience will continue to be ever more important as even newer neurotoxins are discovered.
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Survey of Selective NeurotoxinsKostrzewa, Richard M. 01 January 2014 (has links)
There has been an awareness of nerve poisons from ancient times. At the dawn of the twentieth century, the actions and mechanisms of these poisons were uncovered by modern physiological and biochemical experimentation. However, the era of selective neurotoxins began with the pioneering studies of R. Levi-Montalcini through her studies of the neurotrophin "nerve growth factor" (NGF), a protein promoting growth and development of sensory and sympathetic noradrenergic nerves. An antibody to NGF, namely, anti-NGF - developed in the 1950s in a collaboration with S. Cohen - was shown to produce an "immunosympathectomy" and virtual lifelong sympathetic denervation. These Nobel Laureates thus developed and characterized the first identifiable selective neurotoxin. Other selective neurotoxins were soon discovered, and the compendium of selective neurotoxins continues to grow, so that today there are numerous selective neurotoxins, with the potential to destroy or produce dysfunction of a variety of phenotypic nerves. Selective neurotoxins are of value because of their ability to selectively destroy or disable a common group of nerves possessing (1) a particular neural transporter, (2) a unique set of enzymes or vesicular transporter, (3) a specific type of receptor or (4) membranous protein, or (5) other uniqueness. The era of selective neurotoxins has developed to such an extent that the very definition of a "selective" neurotoxin has warped. For example, (1) N-methyl-D- aspartate receptor (NMDA-R) antagonists, considered to be neuroprotectants by virtue of their prevention of excitotoxicity from glutamate receptor agonists, actually lead to the demise of populations of neurons with NMDA receptors, when administered during ontogenetic development. The mere lack of natural excitation of this nerve population, consequent to NMDA-R block, sends a message that these nerves are redundant - and an apoptotic cascade is set in motion to eliminate these nerves. (2) The rodenticide rotenone, a global cytotoxin that acts mainly to inhibit complex I in the respiratory transport chain, is now used in low dose over a period of weeks to months to produce relatively selective destruction of substantia nigra dopaminergic nerves and promote alpha-synuclein deposition in brain to thus model Parkinson's disease. Similarly, (3) glial toxins, affecting oligodendrocytes or other satellite cells, can lead to the damage or dysfunction of identifiable groups of neurons. Consequently, these toxins might also be considered as "selective neurotoxins," despite the fact that the targeted cell is nonneuronal. Likewise, (4) the dopamine D2-receptor agonist quinpirole, administered daily for a week or more, leads to development of D2-receptor supersensitivity - exaggerated responses to the D2-receptor agonist, an effect persisting lifelong. Thus, neuroprotectants can become "selective" neurotoxins; nonspecific cytotoxins can become classified as "selective" neurotoxins; and receptor agonists, under defined dosing conditions, can supersensitize and thus be classified as "selective" neurotoxins. More examples will be uncovered as the area of selective neurotoxins expands. The description and characterization of selective neurotoxins, with unmasking of their mechanisms of action, have led to a level of understanding of neuronal activity and reactivity that could not be understood by conventional physiological observations. This chapter will be useful as an introduction to the scope of the field of selective neurotoxins and provide insight for in-depth analysis in later chapters with full descriptions of selective neurotoxins.
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Comparing Immune Responses to Inactivated Vaccines Against SARS-CoV-2 Between People Living With HIV and HIV-Negative Individuals: A Cross-Sectional Study in ChinaHuang, Xiaojie, Yan, Ying, Su, Bin, Xiao, Dong, Yu, Maohe, Jin, Xia, Duan, Junyi, Zhang, Xiangjun, Zheng, Shimin, Fang, Yuan, Zhang, Tong, Tang, Weiming, Wang, Lunan, Wang, Zixin, Xu, Junjie 28 January 2022 (has links)
This study compared the immunogenicity of inactivated SARS-CoV-2 vaccines between people living with HIV (PLWH) and HIV-negative individuals. We recruited 120 PLWH and 53 HIV-negative individuals aged 18-59 years who had received an inactivated SARS-CoV-2 vaccine in two Chinese cities between April and June 2021. Blood samples were tested for immunogenicity of the inactivated SARS-CoV-2 vaccines. The prevalence and severity of adverse events associated with SARS-CoV-2 vaccines were similar between PLWH and HIV-negative individuals. The seropositivity of neutralizing activity against authentic SARS-CoV-2, of the total amount of antibody (total antibody) and of S-IgG were 71.3%, 81.9%, and 92.6%, respectively, among fully vaccinated PLWH. Among all participants, PLWH had lower neutralizing activity, total antibody, S-IgG, and T-cell-specific immune response levels, compared to HIV-negative individuals, after controlling for types of vaccine, time interval between first and second dose, time after receiving the second dose, and sociodemographic factors. PLWH with a longer interval since HIV diagnosis, who received their second dose 15-28 days prior to study commencement, and who had an interval of ≥21 days between first and second dose had higher neutralizing activity levels. The immunogenicity of the inactivated SARS-CoV-2 vaccines was lower among PLWH as compared to HIV-negative individuals. Vaccination guideline specific for PLWH should be developed.
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Development of High-throughput Membrane Filtration Techniques for Biological and Environmental Applications / Development of High-throughput Membrane Filtration TechniquesKazemi, Amir Sadegh 11 1900 (has links)
Membrane filtration processes are widely utilized across different industrial sectors for biological and environmental separations. Examples of the former are sterile filtration and protein fractionation via microfiltration (MF) and ultrafiltration (UF) while drinking water treatment, tertiary treatment of wastewater, water reuse and desalination via MF, UF, nanofiltration (NF) and reverse-osmosis (RO) are examples of the latter. A common misconception is that the performance of membrane separation is solely dependent on the membrane pore size, whereas a multitude of parameters including solution conditions, solute concentration, presence of specific ions, hydrodynamic conditions, membrane structure and surface properties can significantly influence the separation performance and the membrane’s fouling propensity. The conventional approach for studying filtration performance is to use a single lab- or pilot-scale module and perform numerous experiments in a sequential manner which is both time-consuming and requires large amounts of material. Alternatively, high-throughput (HT) techniques, defined as the miniaturized version of conventional unit operations which allow for multiple experiments to be run in parallel and require a small amount of sample, can be employed. There is a growing interest in the use of HT techniques to speed up the testing and optimization of membrane-based separations. In this work, different HT screening approaches are developed and utilized for the evaluation and optimization of filtration performance using flat-sheet and hollow-fiber (HF) membranes used in biological and environmental separations. The effects of various process factors were evaluated on the separation of different biomolecules by combining a HT filtration method using flat-sheet UF membranes and design-of-experiments methods. Additionally, a novel HT platform was introduced for multi-modal (constant transmembrane pressure vs. constant flux) testing of flat-sheet membranes used in bio-separations. Furthermore, the first-ever HT modules for parallel testing of HF membranes were developed for rapid fouling tests as well as extended filtration evaluation experiments. The usefulness of the modules was demonstrated by evaluating the filtration performance of different foulants under various operating conditions as well as running surface modification experiments. The techniques described herein can be employed for rapid determination of the optimal combination of conditions that result in the best filtration performance for different membrane separation applications and thus eliminate the need to perform numerous conventional lab-scale tests. Overall, more than 250 filtration tests and 350 hydraulic permeability measurements were performed and analyzed using the HT platforms developed in this thesis. / Thesis / Doctor of Philosophy (PhD) / Membrane filtration is widely used as a key separation process in different industries. For example, microfiltration (MF) and ultrafiltration (UF) are used for sterilization and purification of bio-products. Furthermore, MF, UF and reverse-osmosis (RO) are used for drinking water and wastewater treatment. A common misconception is that membrane filtration is a process solely based on the pore size of the membrane whereas numerous factors can significantly affect the performance. Conventionally, a large number of lab- or full-scale experiments are performed to find the optimum operating conditions for each filtration process. High-throughput (HT) techniques are powerful methods to accelerate the pace of process optimization—they allow for multiple experiments to be run in parallel and require smaller amounts of sample. This thesis focuses on the development of different HT techniques that require a minimal amount of sample for parallel testing and optimization of membrane filtration processes with applications in environmental and biological separations. The introduced techniques can reduce the amount of sample used in each test between 10-50 times and accelerate process development and optimization by running parallel tests.
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