Letteratura scientifica selezionata sul tema "Beta-cell protection"

Although currently available drugs are useful in controlling early onset complications of diabetes, serious late onset complications appear in a large number of patients. Considering the physiopathology of diabetes, preventing beta cell degeneration and stimulating the endogenous regeneration of islets will be essential approaches for the treatment of insulin-dependent diabetes mellitus. The current review focused on phytochemicals, the antidiabetic effect of which has been proved by pancreatic beta cell protection/regeneration. Among the hundreds of plants that have been investigated for diabetes, a small fraction has shown the regenerative property and was described in this paper. Processes of pancreatic beta cell degeneration and regeneration were described. Also, the proposed mechanisms for the protective/regenerative effects of such phytochemicals and their potential side effects were discussed.

Abstract A beta 2-microglobulin (beta 2m)-deficient variant of YAC-1, A.H-2-, was transfected with a genomic beta 2m clone. Transfected cells were used to investigate the role of beta 2m in IFN-induced protection from NK cell lysis. IFN-gamma treatment of the NK-sensitive murine YAC-1 lymphoma results in reduced sensitivity to NK cell-mediated lysis in parallel with increased expression of its constitutively low MHC class I expression. It was previously shown that the A.H-2- variant had lost both these capacities, although it retained other responses to IFN-gamma. Here beta 2m transfection restored the YAC-1 phenotype with respect to an inducible expression of MHC class I molecules and a concomitant protection from NK cell lysis after treatment with IFN-gamma. In the absence of IFN-gamma the NK sensitivity of the transfectants did not differ significantly from A.H-2-. A similar protection from NK cell lysis, in parallel with enhanced MHC class I expression, was observed for in vivo-passaged beta 2m transfectants whereas no protection was found for in vivo-passaged A.H-2- cells. The present study provides evidence that the IFN-gamma-mediated protection from NK cell lysis is dependent on beta 2m expression in the YAC-1 lymphoma. Restoration of MHC class I assembly, transport, and concomitantly an IFN-gamma augmentable cell surface expression of MHC class I molecules is a possible explanation for the effect of beta 2m.

Type 2 diabetes (T2D) is characterized by chronic hyperglycemia secondary to the decline of functional beta-cells and is usually accompanied by a reduced sensitivity to insulin. Whereas altered beta-cell function plays a key role in T2D onset, a decreased beta-cell mass was also reported to contribute to the pathophysiology of this metabolic disease. The decreased beta-cell mass in T2D is, at least in part, attributed to beta-cell apoptosis that is triggered by diabetogenic situations such as amyloid deposits, lipotoxicity and glucotoxicity. In this review, we discussed the molecular mechanisms involved in pancreatic beta-cell apoptosis under such diabetes-prone situations. Finally, we considered the molecular signaling pathways recruited by glucagon-like peptide-1-based therapies to potentially protect beta-cells from death under diabetogenic situations.

Abstract The development of experimental autoimmune encephalomyelitis (EAE) in Lewis rats is mediated by V beta 8.2+ T cells specific for myelin basic protein. One consequence of this biased expression of V beta 8.2 is the spontaneous development of regulatory T cells and antibodies against residues 39-59 of the V beta 8.2 sequence. Moreover, a synthetic V beta 8.2-39-59 peptide could induce protection against and speed recovery from EAE. T cells and antibodies specific for V beta 8.2-39-59 could transfer protection from EAE. Recently, we reported that the protective T cell epitope is subsumed within the V beta 8-44-54 sequence. We now report that protection induced by V beta 8-44-54 lasted at least 102 days and produced "split tolerance," enhancing anti-myelin basic protein antibody titers but reducing anti-myelin basic protein T cell frequency. The shorter V beta 8-44-54 peptide induced a distinct set of antibodies that did not cross-react with the longer V beta 8.2-39-59 peptide, although both specificities could stain V beta 8.2+ T cells and were equally protective against EAE. However, the V beta 8.2-39-59 peptide, but not the V beta 8-44-54 peptide, would appear to represent the natural idiotope: antibodies to V beta 8.2-39-59 that develop spontaneously during EAE could be boosted to higher titers only by the V beta 8.2-39-59, but not by other TCR peptides from the V beta 8.2 sequence, including V beta 8-44-54 that contains the functional T cell epitope. These results suggest that natural processing of the TCR V beta-chain favors the formation of a peptide that resembles the V beta 8.2-39-59 sequence. The B cell epitope present on the V beta 8-44-54 sequence was evident only in the absence of residues 39-43 and 55-59, suggesting that the two peptides possess distinct conformations. However, the V beta 8-44-54 B cell epitope is most likely expressed on the V beta 8.2+ T cells, either as a low affinity determinant on the intact TCR alpha/beta heterodimer or as a cryptic epitope bound in the cleft of surface MHC molecules.

Abstract The recovery process in experimental autoimmune encephalomyelitis (EAE) in Lewis rats is characterized by an increasing diversity of T cell clones directed at secondary epitopes of myelin basic protein. Of particular interest, residues 55 to 69 of guinea pig basic protein could induce protection against EAE. A nonencephalitogenic T cell clone, C455-69, that was specific for this epitope transferred protection against both active and passive EAE. Clone C4 was found to express V beta 8.6 in its Ag receptor, and residues 39 to 59 of the TCR V beta 8.6 sequence were found to be highly crossreactive with the corresponding residues 39 to 59 of TCR V beta 8.2, which is known to induce protective anti-idiotypic T cells and antibodies. Like the TCR V beta 8.2 peptide, the V beta 8.6 sequence induced autoregulation and provided effective treatment of established EAE. Thus, the EAE-protective effect of the guinea pig basic protein 55-69 sequence was most likely mediated by T cell clones such as C4 that could efficiently induce anti-TCR immunity directed at a cross-reactive regulatory idiotope.

The aim of our work was to test whether thymosin beta 4 protected endothelial progenitor cells against apoptosis induced by advanced glycation endproducts and investigate the underlying mechanism. Treatment with thymosin beta 4 or transfection with microRNA-34a inhibitor enhanced cell viability, reduced apoptosis, abated oxidative stress, and attenuated mitochondrial dysfunction in endothelial progenitor cells exposed to advanced glycation endproducts. Incubation with advanced glycation endproducts led to increased levels of microRNA-34a, which was attenuated by treatment with thymosin beta 4. Transfection with microRNA-34a reversed the beneficial effect of thymosin beta 4 against injuries induced by advanced glycation endproducts. The microRNA-34a could directly bind to the 3′UTRs of the mRNA of B-cell lymphoma 2, and thymosin beta 4 treatment upregulated B-cell lymphoma 2 expression in endothelial progenitor cells exposed to advanced glycation endproducts. More importantly, knockdown of B-cell lymphoma 2 abolished the protection of thymosin beta 4 and microRNA-34a inhibitor against advanced glycation endproducts. In conclusion, inhibition of microRNA-34a mediated protection of thymosin beta 4 in endothelial progenitor cells against advanced glycation endproducts by targeting B-cell lymphoma 2, which was helpful for understanding the therapeutic potential of thymosin beta 4 for diabetic patients.

Abstract Host defenses against experimental listeriosis in mice involve neutrophils, macrophages, NK cells, and alpha beta T cells. Recently gamma delta T cells have also been implicated in antilisterial resistance. However, their specific role has remained unclear. Here we show that efficient resistance to infection by this bacterium depends on the functions of both alpha beta and gamma delta T cells in both primary and secondary responses. We also present evidence that these functions are complementary. In the livers of alpha beta T cell-depleted mice, bacteria grow to large numbers within hepatocytes but are infrequently found extracellularly. Granulomatous lesions are more frequent and somewhat larger than in normal controls, but remain focal. Neutrophils are absent from liver lesions in these mice. In contrast, the livers of gamma delta T cell-depleted mice contain many extracellular bacteria, but do not show hepatocytes containing large numbers of Listeria. Liver lesions in gamma delta T cell-depleted mice are far more extensive than in normal controls or in alpha beta T cell-depleted mice, and contain large numbers of neutrophils. Particularly in secondary listeriosis, gamma delta T cell-depleted mice show vast coalescent areas of necrotic liver parenchyma within 48 h after infection. Because the bacterial numbers in gamma delta T cell-depleted mice remain lower than in alpha beta T cell-depleted mice, increased mortality in the former may be in part caused by liver failure. We conclude that gamma delta T cells are required to control inflammatory reactivity and to prevent excessive liver damage during the immune response to Listeria monocytogenes.

Thesis (PhD)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: Insights into the role of oxidative stress and pancreatic β-cell dysfunction in the pathogenesis of type 2 diabetes (T2D) reveals an opportunity for the development of novel therapeutics that directly protect and preserve β-cells. The protective role of dietary antioxidants, such as plant polyphenols, against oxidative stress induced diseases, including T2D, is increasingly under scrutiny. Polyphenol-rich extracts of Cyclopia spp, containing mangiferin, may provide novel therapeutics. An aqueous extract of unfermented Cyclopia maculata, containing more than 6 % mangiferin, was assessed for its protective effect in pancreatic β-cells in vitro, ex vivo and in vivo under conditions characteristic of T2D. The effect of mangiferin was also evaluated in vitro and ex vivo, with N-acetyl cysteine (NAC) as an antioxidant control. In this study, we established in vitro toxicity models in RIN-5F insulinoma cells based on conditions β-cells are exposed to in T2D; i.e. lipotoxicity, inflammation and oxidative stress conditions. To achieve this, cells were exposed to the following stressors: palmitic acid (PA), a pro-inflammatory cytokine combination and streptozotocin (STZ), respectively. Thereafter, the ability of the C. maculata extract, mangiferin and NAC to protect RIN-5F cells from the effects of these stressors was assessed by measuring β-cell viability, function and oxidative stress. Cell viability was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, adenosine triphosphate and annexin-V and propidium iodide assays. Cell function was evaluated by measuring glucose stimulated insulin secretion, cell proliferation and cellular calcium. To assess oxidative stress in the RIN-5F cells, diaminofluorescein-FM and dihydroethidium fluorescence, and superoxide dismutase enzyme activity were measured. The in vitro findings were then verified in isolated pancreatic rat islets using methods and models established in the RIN-5F experiments. The protective effect of the extract, NAC and metformin was assessed in STZ induced diabetic Wistar rats, using two treatment regimes, i.e. by treating rats with established diabetes and by pretreating rats prior to induction of diabetes by STZ. Glucose metabolism, oxidative stress and pancreatic morphology were assessed by performing an oral glucose tolerance test, measuring serum insulin, triglycerides, nitrites, catalase and glutathione. Hepatic thiobarbituric acid reactive substances and nitrotyrosine were also assessed. Immunohistochemical labelling of pancreata with insulin, glucagon and MIB-5 was used for morphological assessment. The extract improved β-cell viability, function and attenuated oxidative stress, most apparently in STZ and PA induced toxicity models comparable with NAC both in vitro and in isolated islets. Mangiferin was not as effective, showing only marginal improvement in RIN-5F cell and islet function, and oxidative stress. Pretreatment of STZ induced diabetic Wistar rats with extract was as effective as, if not better than, metformin in improving glucose tolerance, hypertriglyceridaemia and pancreatic islet morphology related to improved β-cell function. This study demonstrated that the aqueous extract of unfermented C. maculata was able to protect pancreatic β-cells from STZ and PA induced toxicity in vitro and ex vivo. In vivo, pretreatment with the extract improved glucose metabolism and pancreatic islet morphology in STZ induced diabetic Wistar rats.
AFRIKAANSE OPSOMMING: Insigte oor die rol wat oksidatiewe stres en pankreas β-sel disfunksie in die patogenese van tipe 2-diabetes (T2D) speel, bied 'n geleentheid vir die ontwikkeling van nuwe terapeutiese middels wat β-selle direk daarteen beskerm. Die beskermende rol van antioksidante in die dieët soos plantaardige polifenole teen oksidatiewe stres geinduseerde siektes soos T2D, is toenemend onder die soeklig. Polifenolryk ekstrakte van Cyclopia spp wat mangiferin bevat mag nuwe terapeutiese middels lewer. ‘n Waterekstrak van ongefermenteerde Cyclopia maculata wat meer as 6% mangiferin bevat, is ondersoek vir sy beskermende effek op pankreas ß-selle in vitro, ex vivo en in vivo teen kondisies kenmerkend aan T2D. Die effek van mangiferin is ook in vitro en ex vivo geëvalueer, met N-asetielsistien (NAC) as 'n antioksidant kontrole. In hierdie studie is in vitro toksisiteitsmodelle in RIN-5F insulinoomselle gevestig. Die modelle is gebaseer op toestande waaraan β-selle blootgestel word tydens T2D; d.w.s. lipotoksisiteit, inflammasie en oksidatiewe stres. Hiervoor is die selle aan die volgende stressors blootgestel: palmitiensuur (PA), ‘n pro-inflammatoriese sitokien mengsel en streptozotosien (STZ). Vervolgens is die vermoë van die C. maculata ekstrak, mangiferin en NAC om die RIN-5Fselle teen hierdie stressors te beskerm, beoordeel deur die meting van β-sellewensvatbaarheid, funksie en oksidatiewe stres. Sellewensvatbaarheid is bepaal met 3-(4,5-dimetielthiazol-2-yl)-2,5-difenieltetrazolium bromied, adenosientrifosfaat en anneksien-V and propidium jodied toetse. Selfunksie is geëvalueer d.m.v. glukose gestimuleerde insuliensekresie, selproliferasie en sellulêre kalsium bepaling. Oksidatiewe stres in die RIN-5Fselle is geëvalueer d.m.v. diaminofluorescein-FM en dihidroethidium fluoressensie bepalings, asook meting van superoksied dismutase ensiemaktiwiteit. Die in vitro bevindings is daarna in geїsoleerde rot pankreaseilande bevestig deur die metodes en modelle wat in die RIN-5F eksperimente gebruik is. Die antidiabetiese effekte van die ekstrak, NAC en metformien in STZ-geїnduseerde diabetiese Wistar rotte is bepaal d.m.v. twee behandlingsregimes, d.w.s. die behandeling van rotte met gevestigde diabetes of deur die behandeling voor die induksie van diabetes te begin. Glukose metabolisme, oksidatiewe stres en veranderinge in die pankreasmorfologie is ondersoek d.m.v. orale glukose toleransie toetse en die bepaling van serum insulien, trigliseriedes, nitriete, katalase en glutationien. Hepatiese tiobarbituursuur reaktiewe stowwe en nitrotirosien is ook geëvalueer. Immunohistochemiese kleuring van pankreas snitte is gebruik vir morfologiese assessering van insulien, glukagon en MIB-5. Die ekstrak het mees opvallend β-sel lewensvatbaarheid en funksie verbeter, terwyl oksidatiewe stres verminder is in die STZ- en PA-geїnduseerde toksisiteitmodelle. Bogenoemde effekte van die ekstrak in vitro en in die geїsoleerde eilande was vergelykbaar met die van NAC. Mangiferin was minder effektief, met slegs ‘n marginale verbetering in die funksie van RIN-5Fselle en eilande, asook t.o.v. oksidatiewe stres. Behandeling van die Wistar rotte met die ekstrak voor induksie van diabetes met STZ was net so effektief, of selfs beter as metformien in terme van verbeterde glukosetoleransie, trigliseriedvlakke en die morfologie van pankreas eilande wat verband gehou het met β-sel funksie. Hierdie studie het getoon dat die waterekstrak van ongefermenteerde C. maculata pankreas β-selle teen veral STZ- en PA-geїnduseerde toksisiteit in vitro en ex vivo beskerm het. In vivo het behandeling met die ekstrak voor en na induksie van diabetes, glukosemetabolisme en die morfologie van pankreas eilande in STZ-geїnduseerde diabetiese Wistar rotte verbeter.

PURPOSE: Transplantation of pancreatic islets to Type 1 diabetes patients is hampered by inflammatory reactions at the transplantation site leading to dysfunction and death of insulin producing beta-cells. Recently we have shown that co-transplantation of neural crest stem cells (NCSCs) together with the islet cells improves transplantation outcome. The aim of the present investigation was to describe in vitro interactions between NCSCs and insulin producing beta-TC6 cells that may mediate protection against cytokine-induced beta-cell death. PROCEDURES: Beta-TC6 and NCSC cells were cultured either alone or together, and either with or without cell culture inserts. The cultures were then exposed to the pro-inflammatory cytokines IL-1β and IFN-γ for 48 hours followed by analysis of cell death rates (flow cytometry), nitrite production (Griess reagent), protein localization (immunofluorescence) and protein phosphorylation (flow cytometry). RESULTS: We observed that beta-TC6 cells co-cultured with NCSCs were protected against cytokine-induced cell death, but not when separated by cell culture inserts. This occurred in parallel with (i) augmented production of nitrite from beta-TC6 cells, indicating that increased cell survival allows a sustained production of nitric oxide; (ii) NCSC-derived laminin production; (iii) decreased phospho-FAK staining in beta-TC6 cell focal adhesions, and (iv) decreased beta-TC6 cell phosphorylation of ERK(T202/Y204), FAK(Y397) and FAK(Y576). Furthermore, co-culture also resulted in cadherin and beta-catenin accumulations at the NCSC/beta-TC6 cell junctions. Finally, the gap junction inhibitor carbenoxolone did not affect cytokine-induced beta-cell death during co-culture with NCSCs. CONCLUSION: In summary, direct contacts, but not soluble factors, promote improved beta-TC6 viability when co-cultured with NCSCs. We hypothesize that cadherin junctions between NCSC and beta-TC6 cells promote powerful signals that maintain beta-cell survival even though ERK and FAK signaling are suppressed. It may be that future strategies to improve islet transplantation outcome may benefit from attempts to increase beta-cell cadherin junctions to neighboring cells.

En 2019, la Fédération Internationale du Diabète a révélé que près de 500 millions de personnes étaient atteintes de diabète dans le monde. On estime que cette incidence atteindra les 700 millions de personnes en 2045. Outre, l’aspect financier de la prise en charge, le diabète est un véritable enjeu de santé publique. En effet, l’environnement hyperglycémique délétère associé au diabète est à l’origine de graves complications pouvant altérer le fonctionnement de nombreux organes tels que le cœur, le cerveau ou encore le rein. La résistance à l’insuline associée à la détérioration de la sécrétion d’insuline et à la perte de la masse cellulaire bêta pancréatique constituent les principales caractéristiques du diabète de type 2. Ainsi, afin d’améliorer la prise en charge des patients diabétiques, l’identification d’une approche thérapeutique maîtrisée permettant de protéger la masse cellulaire bêta et de favoriser la sécrétion d’insuline uniquement en réponse au glucose et ce, sans effets secondaires, apparaît idéale.Les précédents travaux du laboratoire ont identifié le PE endogène et ses dérivés synthétiques la Spadine et la Mini-Spadine comme des inhibiteurs sélectifs des canaux potassiques TREK-1 au fort potentiel antidépresseur et impliqués dans la sécrétion de sérotonine, la prolifération et la survie neuronale. Au niveau périphérique, la Spadine a été décrite in vitro et in vivo comme un peptide à l’effet incrétine comparable à celui de l’exendine-4, un antidiabétique couramment utilisé en clinique. Ainsi, à la suite de cette étude et par analogie aux effets protecteurs observés sur le neurone, nous avons émis l’hypothèse que le PE et ses dérivés pouvaient avoir un rôle bénéfique dans les mécanismes de survie de la cellule bêta pancréatique.Dans ce manuscrit, nous démontrons que le PE endogène et ses dérivés protègent les cellules bêta de l’apoptose induite par la présence chronique de l’interleukine pro-inflammatoire et diabétogène IL-1β, ainsi que d’un choc toxique aigu induit par la staurosporine. De plus, l’analyse des mécanismes intracellulaires révèle que ces peptides provoquent une augmentation de la concentration en calcium intracellulaire, activent les voies prolifératives et de survie ERK et Akt, et maintiennent l’activité du facteur transcriptionnel CREB dans un environnement délétère via un mécanisme dépendant des calmodulines kinases.Ainsi, ces travaux de thèse montrent que le PE et ses dérivés synthétiques protègent la cellule bêta pancréatique et initient des processus cellulaires vertueux par une voie de signalisation originale indépendante de la PKA, où le potentiel de membrane et le calcium occupent un rôle crucial. Ces données suggèrent le PE endogène et ses dérivés synthétiques comme une nouvelle classe de peptides protecteurs des cellules bêta pancréatiques
In 2019, the International Diabetes Federation revealed that nearly 500 million people have diabetes worldwide. It is estimated that this incidence will reach 700 million people by 2045. In addition to the financial aspect of treatment, diabetes is a real public health issue. Indeed, the deleterious hyperglycemic environment associated with diabetes is could induce serious complications, leading to a functional alteration of many organs such as the heart, the brain or the kidney. Insulin resistance associated with the deterioration of insulin secretion and the loss of pancreatic beta cell mass are the main characteristics of type 2 diabetes. Thus, in order to improve the management of diabetic patients, the identification of a controlled therapeutic approach to protect beta cell mass and promote insulin secretion only in response to glucose and without side effects, appears ideal.The laboratory has identified the endogenous PE and its synthetic derivatives Spadin and Mini-Spadin as selective inhibitors of TREK-1 potassium channels. By this mechanism, the peptides showed also a strong antidepressant potential by modulating serotonin secretion, neuronal proliferation and survival. At the peripheral level, Spadin has been described in vitro and in vivo as a peptide with an incretin effect comparable to that of exendin-4, an antidiabetic commonly used in the clinic. Thus, following this study and by analogy to the protective effects observed on the neuron, we hypothesized that PE and its derivatives may have a beneficial role in the survival mechanisms in the pancreatic beta-cell.In this thesis, we demonstrate that endogenous PE and its derivatives protect beta cells from apoptosis induced by the chronic presence of the pro-inflammatory and diabetogenic interleukin IL-1β, as well as from an acute toxic shock induced by staurosporine. Furthermore, analysis of intracellular mechanisms reveals that these peptides cause an increase in intracellular calcium concentration, activate the ERK and Akt proliferative and survival pathways, and maintain CREB transcriptional factor activity in a deleterious environment via a calmodulin kinase-dependent pathway.Thus, this work shows that PE and its synthetic derivatives protect the pancreatic beta-cell and initiate virtuous cellular processes through an original PKA-independent signaling pathway, where membrane potential and calcium play a crucial role. This suggests the sortilin-derived peptides as a new class of pancreatic beta-cell protective molecules

Type 1 diabetes is a disease resulting from the progressive immune-mediated destruction of insulin producing β-cells. In order to understand more about diabetes we need to understand the mechanisms governing β-cell death.

The leukemia drug Gleevec is a tyrosine kinase inhibitor that targets c-Abl. Surprisingly, Gleevec also counteracts Type 2 diabetes and acts as a cell death inhibiting agent, via inhibition c-Abl. Since both Type 1 and Type 2 diabetes are characterized by an increased β-cell death, and the role of c-Abl is unknown in β-cells, we wanted to investigate the following:

1.Does Gleevec act via inhibition of c-Abl in β-cells?

2.Can Gleevec treatment prevent beta-cell death and diabetes?

3.Which downstream signaling pathways are affected by Gleevec?

In paper I, in order to determine whether Gleevec acts by inhibiting c-Abl, we used RNA-interference. Interestingly, siRNA against c-Abl produced by recombinant Dicer mediate almost complete and non-toxic silencing of c-Abl mRNA in dispersed islet cells and conferred protection from streptozotocin and cytokines.

In paper II we show that Gleevec protects β-cells from nitric oxide, pro-inflammatory cytokines and streptozotocin in vitro and that Gleevec can prevent diabetes development in the NOD mouse and the streptozotocin-injected mouse. We also present the hypothesis that Gleevec induces a state resembling ischemic preconditioning.

Paper III presents an additional mechanism by which Gleevec might improve β-cell survival, i.e. via the inhibition of the downstream stress-activated protein kinase c-Jun N-terminal kinase (JNK), the activity of which has been implicated in β-cell death signaling pathways.

In paper IV we explore the interactions between the adaptor protein Shb and c-Abl. We presently show an association between Shb-c-Abl and that Shb is a substrate for the c-Abl kinase that might regulate stress-induced c-Abl activity.

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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
Oxidative stress is the overproduction of reactive oxygen species that cause cell damage and even the death. It is a mechanism related to ischemia and reperfusion, a process that affects several organs and is involved in neurodegenerative diseases, cardiac and/or renal insufficiencies, hepatic dysfunction, among others. The discovery of new antioxidant substances derived from natural sources, is important for the prevention and treatment of these diseases. Beta lapachone is a substance with antioxidant action obtained from sawdust of Ipe wood, a symbolic tree from the Brazilian cerrado. This study aimed to analyze the cytotoxic and antioxidant action of beta lapachone in endothelial cells, in vitro. EA.hy 926 lineage cells were subcultured, treated with different concentrations of beta lapachone and subjected to ischemia and reperfusion. Cytotoxicity and antioxidant action were assessed through the cellular viability analysis by the tetrazolium reduction method. The averages were verified by the Tukey test (5% of significance) and by variance analysis. There was a dose-dependent progression of cytotoxicity in the non-ischemia/reperfusion (control) group and cell viability increase in the ischemia/reperfusion group. However, there was no statistical difference between the concentrations and between groups. Considering the settings of this experiment, Beta lapachone did not present cytotoxic or antioxidant action on endothelial cells.
O estresse oxidativo é o excesso de produção de espécies reativas de oxigênio que causam danos e até a morte das células. É um mecanismo que pode se originar da isquemia e reperfusão, um processo que acomete diversos órgãos e que está envolvido em doenças neurodegenerativas, cardíacas, insuficiências renais, disfunção hepática, entre outras. A necessidade da descoberta de novas substâncias antioxidantes, derivadas de fontes naturais, é importante para a prevenção e tratamento dessas doenças. A beta lapachona é uma substância com ação antioxidante, obtida da serragem da madeira do ipê, vegetação símbolo do cerrado brasileiro. Neste estudo objetivou-se analisar a ação citotóxica e antioxidante da beta lapachona em células endoteliais, in vitro. Células da linhagem EA.hy 926 foram subcultivadas, tratadas com a β lapachona em diferentes concentrações e submetidas à isquemia e reperfusão. A citotoxidade e a ação antioxidante foram obtidas por meio da análise da viabilidade celular pelo método de redução do tetrazólio. As médias foram averiguadas pelo teste de Tukey (5% de significância) e pela análise de variância. Houve progressão dose dependente da citotoxidade no grupo sem isquemia/reperfusão e da viabilidade celular no grupo com isquemia/reperfusão. No entanto, não houve diferença estatística entre as concentrações e entre os grupos. A beta lapachona, nas condições desse experimento, não apresentou ação citotóxica ou antioxidante nas células endoteliais.

A expressão de Smads e de membros da família AP1/ jun-fos podem refletir alterações da via de TGFb, uma via importante para o câncer epidermóide de cabeça e pescoço (HNSCC). Encontramos expressão aumentada dos mRNAs das Smads1-8 em HNSCC em comparação com tecido normal adjacente, por RPA. Além disso, as curvas de sobrevida de Kaplan Meier e a análise multivariada mostraram que a Smad6+ parece ser um fator determinante de bom prognóstico em HNSCC. Quanto a família AP-1, mensurado por Northern blot, somente Fra-1 mostrou-se aumentado no tumor e associado à presença de linfonodos comprometidos. Nossos dados sugerem que a positividade de Smad6 possa ser marcador de bom prognóstico em HNSCC
Smad and AP1 messenger RNA expression may underlie disruptions affecting TGFb signaling in head and neck squamous cell carcinoma (HNSCC). Analysis of Smads1-8 mRNA expression by RPA has shown Smad expression is globally increased in tumor as compared to adjacent normal tissue. Kaplan Meier survival curves and multivariate analysis revealed that Smad6 positivity in tumor was an independent good prognostic factor in HNSCC. In relation to AP-1, as measured by Northern blot, only Fra-1 was overexpressed in tumor and directly related to the presence of lymph node involvement. Our data suggest that Smad6 may be a marker of good prognosis in HNSCC

Malignant cutaneous melanoma is the deadliest form of skin cancer, and a majority of melanoma diagnoses are a result of exposure to ultraviolet (UV) radiation. UV radiation causes DNA damage, which if not repaired correctly via nucleotide excision repair (NER) can result in mutations and melanomagenesis. The melanocortin 1 receptor (MC1R) is a Gs protein coupled receptor located on melanocyte plasma membranes and is involved in protecting the skin from UV induced damage. MC1R signaling results in the activation of two protective pathways: 1) induction of eumelanin synthesis downstream of micropthalmia-associated transcription factor (MITF) and 2) acceleration of NER downstream of ataxia telangiectaseia mutated and Rad3 related (ATR). MC1R signaling, however, also promotes melanocyte proliferation, therefore, the activation of the MC1R pathway must be regulated. The overall hypothesis of this dissertation is that the pathways downstream of MC1R can be manipulated to protect against UV induced damage. Chapter 2 investigates the regulation of the MC1R neutral antagonist human β-defensin 3 (βD3). UV damage did not induce βD3 mRNA expression in ex vivo human skin explants. The induction of βD3 expression instead correlated with inflammatory cytokines including TNF. Chapter 3 investigates the interdependence and cross talk between the two protective pathways downstream of MC1R. We directly tested the effect of MITF on the acceleration of NER and the effect of ATR on the induction of eumelanin synthesis following MC1R activation. MITF was not required for the acceleration of NER as mediated by ATR, however, the induction of transcription of enzymes involved in eumelanin synthesis was dependent upon ATR kinase activity. Finally, Chapter 4 investigates the mechanism by which MC1R promoted proliferation and whether the two UV protective pathways downstream of MC1R could be selectively activated without the risk of melanocyte proliferation. MC1R signaling resulted in activation of the mechanistic target of rapamycin complex 1 (mTORC1), a major regulator of cell growth and proliferation. Inhibition of mTORC1 signaling via rapamycin prevented MC1R induced proliferation in vitro. Rapamycin, however, did not prevent MC1R induced eumelanin synthesis or the acceleration of NER in vitro or in vivo suggesting it is possible to selectively activate the beneficial signaling pathways without the risk of melanocyte proliferation. The results of this dissertation suggest that MC1R signaling could be augmented in individuals to prevent UV induced damage.

This chapter synthesizes explanations that are relevant to each of diabetes, CHD, and stroke, and all three collectively. This synthesis emphasizes glycation of tissues, possibly leading to arterial stiffness and microcirculatory damage. In addition to endothelial pathways to atherosclerosis an external (adventitial) one is proposed, i.e. microcirculatory damage to the vasa vasorum, the network of arterioles that supplies nutrients to the larger arteries themselves. DM₂ plays into this pathway through glycosylation and dyslipidaemia. The cause of the high prevalence of DM₂ in South Asians may lie in protective factors in Europeans not just detrimental ones in South Asians. The high glucose level is considered as an allostatic mechanism controlled by the brain. In addition to the ectopic fat in their liver and pancreas as the cause of beta cell dysfunction, two additional ideas are proposed, i.e. firstly, microcirculatory damage and secondly, glycation, possibly compounded by dietary factors including neoformed contaminants, e.g. AGEs.

Sickle cell disease (SCD) is a major public health challenge. It is a common cause of acute and chronic illness and death, which results from a single amino acid substitution (glutamic acid to valine) at position 6 of the beta (β) chain of the hemoglobin molecule. The pathophysiology is based on the polymerization of deoxygenated hemoglobin S (HbS) and production of irreversibly sickled red cells and vaso-occlusive crisis (VOC). The disease is associated with recurrent episodes of acute pain and organ damage. This chapter highlights the role of SES on the predisposition to VOC and mortality among SCD patients. Findings from this review will enable the development and implementation of policies that can facilitate the effective management of SCD in the region. More awareness and education of parents of children and adults living with SCD are needed to identify factors that predispose patients to VOC and common-sense measures to prevent these triggers. SCD patients should be protected against malaria. The need for nutritional intervention, proper hydration, avoidance of dietary intake of sodium, strenuous physical activity, and extreme weather to reduce the incidence of VOC cannot be overemphasized. Protective immunization and access to effective prophylactic and therapeutic agents should be implemented.

Abstract A NAS battery cell is comprised of a sodium negative electrode and a sulfur positive electrode separated by a solid electrolyte made of beta-alumina, housed within a cylindrical aluminum container. The container is exposed highly corrosive materials, but have to be designed to deliver 4500 charge/ discharge cycles over a 15-year operating life. Studies have shown that a plasma sprayed Fe-75Cr alloy coating provides an effective protection layer. The major challenge to implementing this technology was the development of methods to apply plasma spray coatings in high volume mass production of the cells. This paper describes the development of high speed plasma spray guns optimized for volume manufacturing conditions, and the quality and reliability of NAS cells using this technology demonstrated over a period of nine years in laboratory tests. In April 2002 TEPCO and NGK decided to launch commercial production of NAS batteries. By April 2003, NGK started operation of a new NAS battery manufacturing facility and plasma sprayed aluminum cell containers are now being produced at a rate of over 1300 per day.

We chose to focus our investigations on the effect of the active forms, TTF and AcA, rather than the whole (crude) extract. 1. To establish cultivation program designed to develop lead cultivar/s (which will be selected from the different Af accessions) with the highest yield of the active compounds TTF and/or achillolide A (AcA). These cultivar/s will be the source for the purification of large amounts of the active compounds when needed in the future for functional foods/drug development. This task was completed. 2. To determine the effect of the Af extract, TTF and AcA on neuronal vulnerability to oxidative stress in cultured neurons expressing FAD-linked mutants.Compounds were tested in N2a neuroblastoma cell line. In addition, we have tested the effects of TTF and AcA on signaling events promoted by H₂O₂ in astrocytes and by β-amyloid in neuronal N2a cells. 3. To determine the effect of the Af extract, TTF and AcA on neuropathology (amyloidosis and tau phosphorylation) in cultured neurons expressing FAD-linked mutants. 4. To determine the effect of A¦ extract, AcA and TTF on FAD-linked neuropathology (amyloidosis, tau phosphorylation and inflammation) in transgenic mice. 5. To examine whether A¦ extract, TTF and AcA can reverse behavioral deficits in APPswe/PS1DE9 mice, and affect learning and memory and cognitive performance in these FAD-linked transgenic mice. Background to the topic.Neuroinflammation, oxidative stress, glutamate toxicity and amyloid beta (Ab) toxicity are involved in the pathogenesis of Alzheimer's diseases. We have previously purified from Achilleafragrantissimatwo active compounds: a protective flavonoid named 3,5,4’-trihydroxy-6,7,3’-trimethoxyflavone (TTF, Fl-72/2) and an anti-inflammatory sesquiterpenelactone named achillolide A (AcA). Major conclusions, solutions, achievements. In this study we could show that TTF and AcA protected cultured astrocytes from H₂O₂ –induced cell death via interference with cell signaling events. TTF inhibited SAPK/JNK, ERK1/2, MEK1 and CREBphosphorylation, while AcA inhibited only ERK1/2 and MEK1 phosphorylation. In addition to its protective activities, TTF had also anti-inflammatory activities, and inhibited the LPS-elicited secretion of the proinflammatorycytokinesInterleukin 6 (IL-6) and IL-1b from cultured microglial cells. Moreover, TTF and AcA protected neuronal cells from glutamate and Abcytotoxicity by reducing the glutamate and amyloid beta induced levels of intracellular reactive oxygen species (ROS) and via interference with cell signaling events induced by Ab. These compounds also reduced amyloid precursor protein net processing in vitro and in vivo in a mouse model for Alzheimer’s disease and improvedperformance in the novel object recognition learning and memory task. Conclusion: TTF and AcA are potential candidates to be developed as drugs or food additives to prevent, postpone or ameliorate Alzheimer’s disease. Implications, both scientific and agricultural.The synthesis ofAcA and TTF is very complicated. Thus, the plant itself will be the source for the isolation of these compounds or their precursors for synthesis. Therefore, Achilleafragrantissima could be developed into a new crop with industrial potential for the Arava-Negev area in Israel, and will generate more working places in this region.