967 resultados para immune systems


Relevância:

60.00% 60.00%

Publicador:

Resumo:

Ghrelin is a peptide hormone that was originally isolated from the stomach as the endogenous ligand for the growth hormone secretagogue receptor (GHSR). Ghrelin has many functions, including the regulation of appetite and gut motility, growth hormone release from the anterior pituitary and roles in the cardiovascular and immune systems. Ghrelin and its receptor are expressed in a number of cancers and cancer cell lines and may play a role in processes associated with cancer progression, including cell proliferation, apoptosis, and cell invasion and migration.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Interest in insect small RNA viruses (SRVs) has grown slowly but steadily. A number of new viruses have been analyzed at the sequence level, adding to our knowledge of their diversity at the level of both individual virus species and families. In particular, a number of possible new virus families have emerged. This research has largely been driven by interest in their potential for pest control, as well as in their importance as the causal agents of disease in beneficial arthropods. At the same time, research into known viruses has made valuable contributions to our understanding of an emerging new field of central importance to molecular biology-the existence of RNA-based gene silencing, developmental control, and adaptive immune systems in eukaryotes. Subject to RNA-based adaptive immune responses in their hosts, viruses have evolved a variety of genes encoding proteins capable of suppressing the immune response. Such genes were first identified in plant viruses, but the first examples known from animal viruses were identified in insect RNA viruses. This chapter will address the diversity of insect SRVs, and attempts to harness their simplicity in the engineering of transgenic plants expressing viruses for resistance to insect pests. We also describe RNA interference and antiviral pathways identified in plants and animals, how they have led viruses to evolve genes capable of suppressing such adaptive immunity, and the problems presented by these pathways for the strategy of expressing viruses in transgenic plants. Approaches for countering these problems are also discussed. © 2006 Elsevier Inc. All rights reserved.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Alcoholic liver disease (ALD) is a well recognized and growing health problem worldwide. ALD advances from fatty liver to inflammation, necrosis, fibrosis and cirrhosis. There is accumulating evidence that the innate immune system is involved in alcoholic liver injury. Within the innate and acquired immune systems, the complement system participates in inflammatory reactions and in the elimination of invading foreign, as well as endogenous apoptotic or injured cells. The present study aimed at evaluating the role of the complement system in the development of alcoholic liver injury. First, in order to study the effects of chronic ethanol intake on the complement system, the deposition of complement components in liver and the expression of liver genes associated with complement in animals with alcohol-induced liver injury were examined. It was demonstrated that chronic alcohol exposure leads to hepatic deposition of the complement components C1, C3, C8 and C9 in the livers of rats. Liver gene expression analysis showed that ethanol up-regulated the expression of transcripts for complement factors B, C1qA, C2, C3 and clusterin. In contrast, ethanol down-regulated the expression of the complement regulators factor H, C4bp and factor D and the terminal complement components C6, C8α and C9. Secondly, the role of the terminal complement pathway in the development of ALD was evaluated by using rats genetically deficient in the complement component C6 (C6-/-). It was found that chronic ethanol feeding induced more liver pathology (steatosis and inflammatory changes) in C6-/- rats than in wild type rats. The hepatic triacylglyceride content and plasma alanine aminotransferase activity increased in C6-/- rats, supporting the histopathological findings and elevation of the plasma pro-/anti-inflammatory TNF-/IL-10 ratio was also more marked in C6-/- rats. Third, the role of the alternative pathway in the development of alcoholic liver steatosis was characterized by using C3-/- mice. In C3-/- mice ethanol feeding tended to reduce steatosis and had no further effect on liver triacylglyceride, liver/body weight ratio nor on liver malondialdehyde level and serum alanine aminotransferase activity. In C3-/- mice alcohol-induced liver steatosis was reduced also after an acute alcohol challenge. In both wild type and C3-/- mice ethanol markedly reduced serum cholesterol and ApoA-I levels, phospholipid transfer protein activity and hepatic mRNA levels of fatty acid binding proteins and fatty acid -oxidation enzymes. In contrast, exclusively in C3-/- mice, ethanol treatment increased serum and liver adiponectin levels but down-regulated the expression of transcripts of lipogenic enzymes, adiponectin receptor 2 and adipose differentiation-related protein and up-regulated phospholipase D1. In conclusion, this study has demonstrated that the complement system is involved in the development of alcohol-induced liver injury. Chronic alcohol exposure causes local complement activation and induction of mRNA expression of classical and alternative pathway components in the liver. In contrast expression of the terminal pathway components and soluble regulators were decreased. A deficient terminal complement pathway predisposes to alcoholic liver damage and promotes a pro-inflammatory cytokine response. Complement component C3 contributes to the development of alcohol-induced fatty liver and its consequences by affecting regulatory and specific transcription factors of lipid homeostasis.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Diseases caused by the Lancefield group A streptococcus, Streptococcus pyogenes, are amongst the most challenging to clinicians and public health specialists alike. Although severe infections caused by S. pyogenes are relatively uncommon, affecting around 3 per 100,000 of the population per annum in developed countries, the case fatality is high relative to many other infections. Despite a long scientific tradition of studying their occurrence and characteristics, many aspects of their epidemiology remain poorly understood, and potential control measures undefined. Epidemiological studies can play an important role in identifying host, pathogen and environmental factors associated with risk of disease, manifestation of particular syndromes or poor survival. This can be of value in targeting prevention activities, as well directing further basic research, potentially paving the way for the identification of novel therapeutic targets. The formation of a European network, Strep-EURO, provided an opportunity to explore epidemiological patterns across Europe. Funded by the Fifth Framework Programme of the European Commission s Directorate-General for Research (QLK2.CT.2002.01398), the Strep-EURO network was launched in September 2002. Twelve participants across eleven countries took part, led by the University of Lund in Sweden. Cases were defined as patients with S. pyogenes isolated from a normally sterile site, or non-sterile site in combination with clinical signs of streptococcal toxic shock syndrome (STSS). All participating countries undertook prospective enhanced surveillance between 1st January 2003 and 31st December 2004 to identify cases diagnosed during this period. A standardised surveillance dataset was defined, comprising demographic, clinical and risk factor information collected through a questionnaire. Isolates were collected by the national reference laboratories and characterised according to their M protein using conventional serological and emm gene typing. Descriptive statistics and multivariable analyses were undertaken to compare characteristics of cases between countries and identify factors associated with increased risk of death or development of STSS. Crude and age-adjusted rates of infection were calculated for each country where a catchment population could be defined. The project succeeded in establishing the first European surveillance network for severe S. pyogenes infections, with 5522 cases identified over the two years. Analysis of data gathered in the eleven countries yielded important new information on the epidemiology of severe S. pyogenes infections in Europe during the 2000s. Comprehensive epidemiological data on these infections were obtained for the first time from France, Greece and Romania. Incidence estimates identified a general north-south gradient, from high to low. Remarkably similar age-standardised rates were observed among the three Nordic participants, between 2.2 and 2.3 per 100,000 population. Rates in the UK were higher still, 2.9/100,000, elevated by an upsurge in drug injectors. Rates from these northern countries were reasonably close to those observed in the USA and Australia during this period. In contrast, rates of reports in the more central and southern countries (Czech Republic, Romania, Cyprus and Italy) were substantially lower, 0.3 to 1.5 per 100,000 population, a likely reflection of poorer uptake of microbiological diagnostic methods within these countries. Analysis of project data brought some new insights into risk factors for severe S. pyogenes infection, especially the importance of injecting drug users in the UK, with infections in this group fundamentally reshaping the epidemiology of these infections during this period. Several novel findings arose through this work, including the high degree of congruence in seasonal patterns between countries and the seasonal changes in case fatality rates. Elderly patients, those with compromised immune systems, those who developed STSS and those infected with an emm/M78, emm/M5, emm/M3 or emm/M1 were found to be most likely to die as a result of their infection, whereas those diagnosed with cellulitis, septic arthritis, puerperal sepsis or with non-focal infection were associated with low risk of death, as were infections occurring during October. Analysis of augmented data from the UK found use of NSAIDs to be significantly associated with development of STSS, adding further fuel to the debate surrounding the role of NSAIDs in the development of severe disease. As a largely community-acquired infection, occurring sporadically and diffusely throughout the population, opportunities for control of severe infections caused by S. pyogenes remain limited, primarily involving contact chemoprophylaxis where clusters arise. Analysis of UK Strep-EURO data were used to quantify the risk to household contacts of cases, forming the basis of national guidance on the management of infection. Vaccines currently under development could offer a more effective control programme in future. Surveillance of invasive infections caused by S. pyogenes is of considerable public health importance as a means of identifying long and short-term trends in incidence, allowing the need for, or impact of, public health measures to be evaluated. As a dynamic pathogen co-existing among a dynamic population, new opportunities for exploitation of its human host are likely to arise periodically, and as such continued monitoring remains essential.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

A doença meningocócica (DM) é, ainda hoje, um sério problema de saúde pública, estando associada a elevadas taxas de morbidade e letalidade no mundo. A DM evoca proteção imunológica persistente contra a doença em pessoas com sistema imunológico normal. Em contraste, a proteção induzida por vacinas meningocócicas sempre requer a administração de doses reforço (booster) da vacina. No Brasil, Neisseria meningitidis dos sorogrupos C (MenC) e B (MenB) são as principais causas de DM durante os últimos anos. Atualmente, não existe uma vacina universal contra o meningococo B (MenB). A infecção pelo vírus da imunodeficiência humana (HIV) tem sido apontada como um fator de risco para a mortalidade da DM. Um dos pilares do tratamento do HIV é a utilização de vacinas para doenças imuno-preveníveis. A vacina conjugada anti-MenC é frequentemente recomendada para crianças e adolescentes infectados pelo HIV no Brasil e em muitos outros países. Poucos estudos têm abordado os mecanismos pelos quais as vacinas meningocócicas geram e sustentam a memória imunológica. Os objetivos deste estudo foram: 1) avaliar a resposta de anticorpos bactericidas e de linfócito T (LT) CD4 de memória contra o meningococo após a infecção; 2) avaliar a resposta de anticorpos bactericidas e de LT CD4 de memória e linfócito B de memória (LBm) contra o meningococo após o booster da vacina cubana VA-MENGOC-BC em voluntários imunizados há aproximadamente 17 anos; 3) investigar a resposta de anticorpos funcionais (bactericidas e opsonizantes) após imunização com a vacina conjugada anti-MenC (CRM197) em indivíduos infectados pelo vírus HIV. Após a infecção, 83% dos pacientes diagnosticados como tendo DM pelo teste de látex e/ou cultura tiveram títulos de anticorpos bactericidas protetores, mas não houve uma associação entre os títulos de anticorpos bactericidas e a concentração de imunoglobulina total específica. Houve aumento na frequência de linfócitos T de memória central (TCM) (mediana de 15%) ativados, principalmente após estímulo com a cepa MenC. Nos voluntários pré-vacinados, 3 de 5 indivíduos soroconverteram 7 ou 14 dias após a administração da dose booster. Houve um aumento importante da população TCM 14 dias após o booster, mas sem ativação celular diferenciada dos grupos controles. Observamos resposta positiva de LBm na maioria dos voluntários, mas sem correlação com os anticorpos bactericidas. Em relação aos pacientes HIV positivos, os resultados mostraram a necessidade de uma segunda dose da vacina, já que apenas 15% soroconverteram a uma única dose e a segunda dose resultou em soroconversão de cerca de 55% dos indivíduos. Observamos correlação positiva (r= 0,43) e significativa (P= 0,0007) entre os anticorpos opsonizantes e bactericidas após a vacinação. Não observamos diferenças significativas quando relacionamos os títulos de anticorpos bactericidas com o número absoluto de LT CD4 P= 0,051) e LT CD4 nadir (P= 0,09) entre os pacientes que soroconverteram (n= 43) ou não soroconverteram (n= 106) após a primeira dose. Desta forma, os resultados desta tese indicaram que: 1) os pacientes convalescentes da DM adquirem anticorpos bactericidas após infecção por N. meningitidis; 2) nos voluntários vacinados, a dose booster da vacina anti-MenB não foi plenamente eficaz em ativar a memória imunológica através da produção de anticorpos bactericidas ou ativação de LTm; 3) os pacientes HIV positivos necessitam de uma dose booster da vacina conjugada anti-MenC.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

O presente trabalho investiga um método de detecção de anomalias baseado em sistemas imunológicos artificiais, especificamente em uma técnica de reconhecimento próprio/não-próprio chamada algoritmo de seleção negativa (NSA). Foi utilizado um esquema de representação baseado em hiperesferas com centros e raios variáveis e um modelo capaz de gerar detectores, com esta representação, de forma eficiente. Tal modelo utiliza algoritmos genéticos onde cada gene do cromossomo contém um índice para um ponto de uma distribuição quasi-aleatória que servirá como centro do detector e uma função decodificadora responsável por determinar os raios apropriados. A aptidão do cromossomo é dada por uma estimativa do volume coberto através uma integral de Monte Carlo. Este algoritmo teve seu desempenho verificado em diferentes dimensões e suas limitações levantadas. Com isso, pode-se focar as melhorias no algoritmo, feitas através da implementação de operadores genéticos mais adequados para a representação utilizada, de técnicas de redução do número de pontos do conjunto próprio e de um método de pré-processamento baseado em bitmaps de séries temporais. Avaliações com dados sintéticos e experimentos com dados reais demonstram o bom desempenho do algoritmo proposto e a diminuição do tempo de execução.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Chemokines and their receptors play important roles in nervous and immune systems. Little information, however, exists concerning this gene family in teleost fish. In the present Study, 17 C-C chemokine receptors genes were identified from Danio rerio, 9 from Gasterosteus aculeatus, 10 from Oryzius latipes, 8 from Takifugu rubripes and 5 from Tetraodon nigroviridis. Phylogenetic analysis showed that the orthologs to mammalian CCR6, 7, 8, 9 and CCRL1 receptors were evident in zebrafish, but the clear orthologs to mammalian CCR1, 2, 3, 4, 5 and 10 were not found in zebrafish. The gene structure of zebrafish CCR (zfCCR) was further analyzed. The open reading frame of zfCCR3-1, zfCCR3-3, zfCCR6-1, zfCCR6-2, zfCCR8-2 contain one exon, and two exons were identified for zfCCR2-1, zfCCR2-2, zfCCR4 and zfCCRLI-1, three exons for zfCCR3-2, zfCCR5 and zfCCR7, four exons for zfCCR8-1 and zfCCR9-1. The expression analyses showed that in zebrafish, most C-C chemokine receptor genes Were expressed in fertilized eggs and oocytes, and all the receptor genes were expressed in larval stages. The zfCCR2-2, zfCCR3-1, zfCCR4 and zfCCR6-2 genes were expressed in all normal organs examined, whereas not for zfCCR2-1, zfCCR3-3, zfCCR6-1, zfCCR8-1, zfCCR9-2 and zfCCRL1-2. The expression of zfCCR3-2, zfCCR5, zfCCR7, zfCCR9-1 and zfCCRLI-1 were detected in the majority organs. and zfCCR8-2 and zfCCR8-3 detected only in brain. The differential expression pattern of different paralogues in organs may indicate their difference in function, which requires further investigation. (C) 2008 Elsevier Ltd. All rights reserved.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

A novel fish chemokine receptor gene, chemokine (C-X-C motif) receptor 3 (CXCR3)-like was isolated from the grass carp Ctenopharyngodon idella , with its full-length genomic sequence. The cDNA of grass carp CXCR3-like (gcCXCR3-like) consists of 1261 bp with a 49bp 5'-UTR and a 189 bp 3'-UTR. An open reading frame of 1023 bp encodes a 341-amino acid peptide, with seven transmembrane helices. The deduced amino acid sequence showed the same sequence identities (37.8%) with its counterparts in goat and human. The gcCXCR3-like gene consists of two exons, with one intervening intron, spaced over approximately 2 kb of genomic sequence. Phylogenetic analyses clearly demonstrated that the gcCXCR3-like resembles the CXCR3s of other vertebrates. Real-time PCR analysis showed that gcCXCR3-like was expressed in all tested organs except heart and the expression level of gcCXCR3-like was highest in brain. Flow cytometric analyses showed the positive rate of labelled leukocytes from the healthy grass carp was 17.3%, and the labelled leukocytes were divided into three types by cell sorting. Immunohistochemical localization revealed that gcCXCR3-like expressed in whole brain regions including cerebel, diencephalon, medulla oblongata, optic lobe, and rhinencephalon, and that the labelled leukocytes are actually populations of monocyte and/or phagocyte, lymphocyte and the granulocyte. It is considered that fish CXCR expression and their function may need to be investigated in both nervous and immune systems. (c) 2006 Elsevier Ltd. All rights reserved.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

M J Neal and J Timmis. Timidity: A useful mechanism for robot control? Informatica - special issue on perception and emotion based control, 4(27):197-204, 2003.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Sauze, C and Neal, M. 'Endocrine Inspired Modulation of Artificial Neural Networks for Mobile Robotics', Dynamics of Learning Behavior and Neuromodulation Workshop, European Conference on Artifical Life 2007, Lisbon, Portugal, September 10th-14th 2007.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Flagella confer upon bacteria the ability to move and are therefore organelles of significant bacteriological importance. The innate immune system has evolved to recognise flagellin, (the major protein component of the bacterial flagellar filament). Flagellate microbes can potentially stimulate the immune systems of mammals, and thus have significant immunomodulatory potential. The flagellum-biogenesis genotype and phenotype of Lactobacillus ruminis, an autochthonous intestinal commensal, was studied. The flagellum-biogenesis genotypes of motile enteric Eubacterium and Roseburia species were also investigated. Flagellin proteins were recovered from these commensal species, their amino-termini were sequenced and the proteins were found to be pro-inflammatory, as assessed by measurement of interleukin-8 (IL-8) secretion from human intestinal epithelial cell lines. For L. ruminis, this IL-8 secretion required signalling through Toll Like Receptor 5. A model for the regulation of flagellum-biogenesis in L. ruminis was inferred from transcriptomics data and bioinformatics analyses. Motility gene expression in this species may be under the control of a novel regulator, LRC_15730. Potential promoters for genes encoding flagellin proteins in the Eubacterium and Roseburia genomes analysed were inferred in silico. Relative abundances of the target Eubacterium and Roseburia species in the intestinal microbiota of 25 elderly individuals were determined. These species were found to be variably abundant in these individuals. Motility genes from these species were variably detected in the shotgun metagenome databases generated by the ELDERMET project. This suggested that a greater depth of sequencing, or improved evenness of sequencing, would be required to capture the full diversity of microbial functions for specific target or low abundance species in microbial communities by metagenomics. In summary, this thesis used a functional genomics approach to describe flagellum-mediated motility in selected Gram-positive commensal bacteria. The regulation of flagellum biosynthesis in these species, and the consequences of flagella expression from a host-interaction perspective were also considered.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

The molecular and cellular basis of stress pathology remains an important research question in biological science. A better understanding of this may enable the development of novel approaches for the treatment of stress-related disorders. There is a considerable body of scientific evidence suggesting that dietary lipids, phospholipids and omega-3 polyunsaturated fatty acids (n-3 PUFAs), have therapeutic potential for certain psychiatric disorders. Thus, we proposed n-3 PUFAs as a novel strategy for the prevention or amelioration of stress-related disorders. We hypothesised that these compounds would improve behavioural and neurobiological responses and alter gut microbial composition. Furthermore, we proposed a new mechanism of action exerted by n-3 PUFAs using an in vitro model of stress. Lastly, we explored the protective effects of both phospholipids and n-3 PUFAs against neuroinflammation, which has been shown to contribute to the development of stress-related disorders. We provide further evidence that glucocorticoids, inflammation and early-life stress induce vulnerability to psychopathologies. Specifically, we have demonstrated that corticosterone (CORT) alters cortical neuron and astrocyte percentage composition, reduces brain-derived-neuronal factor (BDNF) expression, and induces glucocorticoid receptor (GR) down-regulation in mixed cortical cultures. Interestingly, we found that lipopolysaccharide (LPS) treatment resulted in an over-expression of pro-inflammatory cytokines in cortical astrocyte cultures. Moreover, we demonstrate that early-life stress induces changes to the monoaminergic and immune systems as well as altered neuroendocrine response to stressors later in life. In addition, we found that early-life stress alters the gut microbiota in adulthood. These data demonstrate that n-3 PUFAs can attenuate CORT-induced cellular changes, but not those caused by LPS, within the cerebral cortex. Similarly, phospholipids were unable to reverse LPS-induced inflammation in cultured astrocytes. In addition, this thesis proposes that n-3 PUFAs may prevent the development or lessen the symptoms of mental illnesses, ameliorating anxiety- and depressive-like symptoms as well as cognitive effects, particularly when administered during neurodevelopment. Such effects may be mediated by GR activation as well as by modification of the gut microbiota composition. Taken together, our findings suggest that n-3 PUFAs have therapeutic potential for stress-related disorders and we provide evidence for the mechanisms by which they may exert these effects. These findings contribute to an exciting and growing body of research suggesting that nutritional interventions may have an important role to play in the treatment of stress-related psychiatric conditions.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Alternative splicing is a general mechanism for regulating gene expression that affects the RNA products of more than 90% of human genes. Not surprisingly, alternative splicing is observed among gene products of metazoan immune systems, which have evolved to efficiently recognize pathogens and discriminate between "self" and "non-self", and thus need to be both diverse and flexible. In this review we focus on the specific interface between alternative splicing and autoimmune diseases, which result from a malfunctioning of the immune system and are characterized by the inappropriate reaction to self-antigens. Despite the widespread recognition of alternative splicing as one of the major regulators of gene expression, the connections between alternative splicing and autoimmunity have not been apparent. We summarize recent findings connecting splicing and autoimmune disease, and attempt to find common patterns of splicing regulation that may advance our understanding of autoimmune diseases and open new avenues for therapy.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Because only 10% of individuals infected with Mycobacterium tuberculosis will eventually develop disease, antigens that are recognized differently by the immune systems of infected healthy and diseased subjects may constitute potential vaccine candidates. Here, the heparin-binding hemagglutinin adhesin (HBHA) is identified as such an antigen. Lymphocytes from 60% of healthy infected individuals (n=25) produced interferon (IFN)-gamma after stimulation with HBHA, compared with only 4% of patients with active tuberculosis (n=24). In the responders, both CD4(+) and CD8(+) cells secreted HBHA-specific IFN-gamma, and the antigen was presented by both major histocompatibility complex class I and II molecules. In contrast to the reduced ability of patients with tuberculosis to produce HBHA-specific IFN-gamma, most of them (82%) produced anti-HBHA antibodies, compared with 36% of the infected healthy subjects. These observations indicate that HBHA is recognized differently by the immune systems of patients with tuberculosis and infected healthy individuals and might provide a marker for protection against tuberculosis.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

As global resistance to conventional antibiotics rises we need to develop new strategies to develop future novel therapeutics. In our quest to design novel anti-infectives and antimicrobials it is of interest to investigate host-pathogen interactions and learn from the complexity of host defense strategies that have evolved over millennia. A myriad of host defense molecules are now known to play a role in protection against human infection. However, the interaction between host and pathogen is recognized to be a multifaceted one, involving countless host proteins, including several families of peptides. The regulation of infection and inflammation by multiple peptide families may represent an evolutionary failsafe in terms of functional degeneracy and emphasizes the significance of host defense in survival. One such family is the neuropeptides (NPs), which are conventionally defined as peptide neurotransmitters but have recently been shown to be pleiotropic molecules that are integral components of the nervous and immune systems. In this review we address the antimicrobial and anti-infective effects of NPs both in vitro and in vivo and discuss their potential therapeutic usefulness in overcoming infectious diseases. With improved understanding of the efficacy of NPs, these molecules could become an important part of our arsenal of weapons in the treatment of infection and inflammation. It is envisaged that targeted therapy approaches that selectively exploit the anti-infective, antimicrobial and immunomodulatory properties of NPs could become useful adjuncts to our current therapeutic modalities. © 2012 Bentham Science Publishers.