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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Inhibition of ADP-induced platelet adhesion to immobilised fibrinogen by nitric oxide: evidence for cGMP-independent mechanisms.

Graham, Anne M, Homer-Vanniasinkam, Shervanthi, Naseem, Khalid M., Oberprieler, Nikolaus G., Roberts, Wayne January 2007 (has links)
No
102

Les échanges entre le parasite et l'hôte dans l'infection par Echinococcus multilocularis : acteurs et conséquences dans le foie / The cross-talk between the parasite and the host in Echinococcus multilocularis infection : actors and consequences in the liver

Wang, Junhua 26 March 2014 (has links)
L'échinococcose alvéolaire (EA) est une maladie parasitaire en relation non seulement avec la destruction hépatique quiaccompagne le développement du stade larvaire (métacestode) d'Echinococcus multilocularis, mais aussi avecl'importante réponse immunitaire granulomateuse qui l'entoure. La plupart des travaux antérieurs visant à caractériser le;relations hôte-parasite ont porté sur les cellules de l'immunité dans des sites éloignés de l'habituelle localisationparasitaire, dans le foie. Ce travail de thèse rapporte les mécanismes impliqués dans les modifications de l'homéostasiehépatique aux différents stades de l'infection, mais aussi l'analyse détaillée des profils de cytokines et chimiokinesprésents dans l'infiltrât cellulaire périparasitaire hépatique, de la présence du transforming growth factor-beta et desautres acteurs de sa voie d'activation, et de l'implication possible du Fibrinogen-like protein-2 (FGL2), une moléculeeffectrice des lymphocytes T-régulateurs récemment identifiée. Les résultats indiquent que la réaction inflammatoire quientoure le métacestode dans le foie contribue significativement à la sécrétion de cytokines et de chimiokines et auxmécanismes fonctionnels immunitaires de l'interaction hôte-parasite ; ils révèlent aussi pour la première foisl'intervention cruciale de FGL2 dans la tolérance vis-à-vis d'£. multilocularis. Ces résultats contribuent à identifier denouvelles cibles pour une thérapeutique immunologique qui permettrait de pallier les conséquences pathologiques del'infection par E. multilocularis et de complémenter l'action seulement parasitostatique des benzimidazoles, seuls agentsthérapeutiques connus actuellement. / Alveolar echinococcosis (AE) is a parasitic disease predominantly caused not only by thé direct hepatic damage whichfollows thé continuous tumor-like prolifération of thé larval stage (métacestode) of Echinococcus multilocularis, but alsoindirectly by thé intense local granulomatous immune response which surrounds thé parasitic tissue. Most of previousstudies which aimed at characterizing thé host-parasite relationship hâve been performed on cells of thé immune responsiin peripheral sites, far from thé usual location of E. multilocularis larvae, i.e. thé liver. This PhD thesis reports on thémechanisms involved in thé changes in hepatic homeostatis at thé various stages of infection, and also on a detailedanalysis of thé cytokine and chemokine profiles in thé hepatic periparasitic cell infiltrate, of thé présence of transforminggrowth factor-beta and other actors of its metabolic pathway, and of thé possible involvement of Fibrinogen-like protein-:(FGL2), a recently identified effector molécule of T-regulatory lymphocytes. Results indicate that thé inflammatoryreaction which surrounds thé métacestode in thé liver significantly contributes to cytokine and chemokine sécrétion and tthé functional immune mechanisms of thé host-parasite interactions; they also reveal for thé first time thé crucialintervention of FGL2 in thé tolérance towards E. multilocularis. Thèse results contribute to identify new targets fortherapeutic immune modulation in order to alleviate thé pathological conséquences of E. multilocularis and tocomplément thé parasitostatic-only action of benzimidazoles, thé currently available chemotherapy of thé disease
103

Effect of dietary fibre on selected haemostatic variables and C-reactive protein / Christina Johanna North

North, Christina Johanna January 2006 (has links)
Motivation: Cardiovascular heart disease (CVD) is the leading cause of death worldwide. Risk markers for CVD include, amongst others, the haemostatic factors tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor type 1 (PAI-1), factor VII (FVII) and fibrinogen and more recently, C-reactive protein (CRP), a sensitive marker of inflammation. Epidemiological studies have demonstrated an inverse association between dietary fibre (DF) consumption and risk factors for CVD and CVD prevalence. Some research indicates that this protection may be related to favourable changes in the haemostatic profile and inflammatory markers. This is applicable for the consumption of total DF, as well as soluble and insoluble fibre. However, clinical intervention trials report conflicting data on the effects of DF on t-PA, PAI-1, FVII, fibrinogen and CRP. In addition, available literature is not clear on the mechanisms through which DF may have favourable effects. Objective: The main objective of this study was to review the results of randomised controlled trials systematically on the effects of DF on the above-mentioned selected haemostatic variables and CRP in healthy adults and subjects with hypertriglyceridaemia and the metabolic syndrome. Methods: Human adult intervention trials, at least two weeks in duration, with an increased and measurable consumption of DF were included. Electronic databases were searched from the earliest record to May/July 2006 and supplemented by crosschecking reference lists of relevant publications. From the literature search, two reviewers identified studies that were rated for quality based on the published methodology. No formal statistical analysis was performed due to the large differences in the study designs of the dietary intervention trials. The primary outcome measures were percentage changes between intervention and control groups, or baseline to end comparisons for t-PA, PAI-1, FVII, fibrinogen and CRP. Results t-PA activity increased significantly (14-167%) over the short and long-term following increased fibre intakes. PAI-1 activity decreased significantly between 15-57% over periods ranging from two to six weeks. These favourable changes in t-PA and PAI-1 occurred in healthy, hypertriglyceridaemic and metabolic syndrome subjects following consumption of diets containing ≥3.3 g/MJ DF and ≥4.5 g/MJ DF respectively. Mechanisms through which DF may affect t-PA and PAI-1 include its lowering effect on insulinaemic and glycaemic responses, decreasing triglycerides which are a precursor of very-low-density lipoproteins, fermentation of DF to short-chain fatty acids, which may reduce free fatty acid concentrations, as well as the role of DF in promoting weight loss. High DF intakes did not have a significant effect on fibrinogen concentrations possibly because of relatively little weight loss, too low DF dosages and maintaining a good nutritional status. Inadequate study designs deterred from meaningful conclusions. Significant decreases in FVll coagulant activity (6-16%) were observed with DF intakes of ≥3.3 g/MJ and concomitant decreased saturated fat intakes and weight loss in healthy and hypertriglyceridaemic subjects. Confounding factors include weight loss and a simultaneous decreased intake of saturated fats. The type of fibre seems to play a role as well. Mechanisms through which DF may reduce FVll concentrations include its effects on triglyceride-rich lipoproteins, insulin and weight loss. Increased DF consumption with dosages ranging between 3.3-7.8 g/MJ were followed by significantly lower CRP concentrations (25-54%), however, simultaneous weight loss and altered fatty acid intakes were also present in all the studies. Mechanisms are inconclusive but may involve the effect of DF on weight loss, insulin, glucose, adiponectin, interleukin-6, free fatty acids and triglycerides. Conclusions: Epidemiological evidence indicates an association between DF and the CVD risk factors t-PA, PAI-1, FVII, fibrinogen and CRP. In general, the risk of CVD may improve with high-fibre intakes as indicated by the favourable changes in some of the parameters. However, simultaneous reduced fat intakes and weight loss presented difficulties in separating out the effects of specific components. Furthermore, DF is consumed in a variety of different forms and different dosages that may have different effects. Overall, the study designs used in the intervention trials prevented significant conclusions. DF did, however, play a role in modifying t-PA, PAI-1, FVII and CRP. Potential effects on fibrinogen were not quantifiable. Recommendations: The results from this investigation provide the motivation for additional controlled clinical research to establish the effect and mechanisms of DF on haemostatic variables and CRP. A critical aspect of future studies would be to set up suitable protocols. The amount of subjects, duration of the trials, confounding factors such as weight loss and altered fat intakes and differentiation between types and dosage of DF are important. DF supplemental studies are recommended as they may be the most suitable method to reach meaningful conclusions. / Thesis (Ph.D. (Nutrition))--North-West University, Potchefstroom Campus, 2007
104

Polimorfismos genéticos relacionados à hemostasia e a sua relação com abortos espontâneos recorrentes / Genetic polymorphism associated with hemostasis and its relationship with recurrent pregnancy losses

Bertinato, Juliano Felix 28 May 2013 (has links)
Aborto espontâneo recorrente (AER) é definido pela presença de três ou mais abortos espontâneos e consecutivos que ocorreram até a 20ª semana de gestação. O AER possui origem multifatorial. Dentre os diversos fatores associados ao AER, alterações na hemostasia podem comprometer o fluxo sanguíneo na placenta e com isso pode aumentar o risco de complicações obstétricas, como o aborto. O objetivo geral deste estudo foi investigar se existe associação entre polimorfismos genéticos (no gene do fibrinogênio (FGB -455G>A e -148C>T), da trombomodulina (THBD 1418C>T), do fator V (F5 1691G>A), da protrombina (F2 20210 G>A), do PAI-1 (SERPINE1 4G/5G) e do TAFI (CPB2<i/> c.505G>A)) e os abortos espontâneos recorrentes (primários e secundários). Os objetivos específicos desse estudo foram: 1- avaliar se existe associação entre os sete polimorfismos e o período em que ocorreram as perdas fetais (precoce ou tardia) e o número de abortos recorrentes; 2- determinar se os haplótipos dos polimorfismos FGB -455G>A e FGB -148C>T estão ou não associados aos abortos primários e secundários. Foram incluídas 256 mulheres com história de abortos espontâneos recorrentes, provenientes do Ambulatório de Obstetrícia da Clínica Obstétrica do Hospital das Clínicas da Faculdade de Medicina da USP e 264 mulheres saudáveis, sem história de aborto espontâneo e que tiveram pelo menos duas gestações normais (grupo controle), pareadas segundo as idades. Amostras de sangue foram obtidas para realização das genotipagens dos polimorfismos por meio de PCR em tempo real (FGB -148C>T, FGB -455G>A, THBD 1418C>T e CBP2 c.505G>A), e PCR-RFLP (SERPINE14G/5G, F5 1691G>A e F2 20210 G>A). As frequências dos genótipos e de alelos para os sete polimorfismos foram semelhantes entre os grupos aborto primário, aborto secundário e grupo controle. Entretanto, quando foi realizada um modelo de regressão logística multivariada saturada, que incluiu as variáveis independentes: F5 1691G>A (referência GG vs GA), F2 20210G>A (referência GG vs GA), CBP2 c.505G>A (referência GG + GA vs AA), THBD 1418C>T (referência CC + CT vs TT), SERPINE1 4G/5G (referência 5G/5G vs 4G/4G + 4G/5G) FGB -455G>A (referência GG vs GA vs AA) e FGB -148C>T (referência CC vs CT vs TT), apenas o polimorfismo FGB -148C>T foi associado ao maior risco de ter aborto primário (OR: 2,91, IC 95% 1,02 - 8,29, p=0,045). Quando os haplótipos para os polimorfismos FGB -455G>A e FGB 148C>T foram considerados, foi observada maior frequência de haplótipo 455G/148T em mulheres com AER primário (3,4%) do que no grupo controle (1,1%), (p=0,030); porém esse efeito não foi observado no AER secundário. Em relação ao número de abortos consecutivos, houve uma tendência (p=0,060) a maior frequência de genótipo TT para o polimorfismo FGB -148C>T no grupo de aborto primário com até três perdas quando comparado com as mulheres do mesmo grupo, porém com número maior de perdas (>3). Em conclusão, os sete polimorfismos quando analisados separadamente, não foram associados ao AER; no entanto, em modelo multivariado de regressão logística, o genótipo TT do polimorfismo FGB 148C>T foi associado com o aumento do risco de ter AER primário. Além disso, foi encontrado maior frequência do haplótipo 455G/148T para os polimorfismos FGB -455G>A e FGB -148C>T em mulheres com aborto primário. / Recurrent pregnancy loss (RPL) is defined by the presence of three or more consecutive losses prior to 20 weeks of gestation. The RPL has multifactorial origin. Among several factors associated with RPL, changes in hemostasis may impair the blood flow in the placenta and thus may increase the risk of obstetric complications, such as pregnancy loss. The general aim of this study was to investigate the association between genetic polymorphisms (in the genes of fibrinogen (FGB -455G>A and -148C>T), thrombomodulin (THBD 1418C>T), factor V (F5 1691G>A), prothrombin (F2 20210 G>A), PAI-1 (SERPINE1 4G/5G) and TAFI (CPB2 c.505G>A)) and recurrent pregnant losses (primary and secondary). The specific aims of this study were: 1 - to evaluate the association between the seven polymorphisms and the period in which the fetal losses occurred (early or late) and the number of recurrent losses; 2 - to determine if the haplotypes of polymorphisms FGB -455G>A and FGB -148C>T present association with primary and secondary pregnant losses. We included 256 women with a RPL history, from the Ambulatory of Obstetrics from Clinical Hospital of the Medical School of USP and 264 healthy women without losses history that have had at least two normal pregnancies (control group), matched according to age. Blood samples were obtained to perform the genotyping of polymorphisms by real-time PCR (FGB -148C>T, FGB -455G>A, THBD 1418C>T and CBP2 c.505G>A), and PCR-RFLP (SERPINE1 4G/5G, F5 1691G>A and F2 20210G>A). The frequencies of genotypes and alleles for the seven genetic polymorphisms were similar in 3 groups. However, when it was performed a model of multivariate logistic regression, which included the independent variables: F5 1691G>A (GG vs GA reference), F2 20210G>A (GG vs GA reference), CBP2 c.505G>A (GG + GA reference vs AA), THBD 1418C>T (reference CC + CT vs TT), SERPINE1 4G/5G (reference 5G/5G + 4G/5G vs 4G/4G), FGB -455G>A (GG reference vs GA vs AA) and FGB - 148C>T (reference CC vs CT vs TT), only the polymorphism FGB 148C>T polymorphism was associated with a higher risk of having primary losses (OR: 2.91, 95% CI 1.02 to 8.29, p = 0.045). When the haplotypes for the polymorphisms FGB -455G>A and FGB -148C>T were considered, had a higher frequency of the haplotype 455G/148T in women with primary RPL (3.4%) than in the control group (1.1%) (p = 0.030); but this effect was not observed in secondary RPL. Regarding the number of successive pregnant losses, there was a trend (p = 0.060) to higher frequency of the TT genotype for FGB -148C>T polymorphism in the group with primary RPL up to three losses when compared with women of the same group, but with loss number higher than three. In conclusion, when the seven genetic polymorphisms were evaluated separately, they do not show association with RPL, however, in multivariate logistic regression analysis, the TT genotype of the FGB -148C>T polymorphism was associated with increased risk for primary RPL. Furthermore, it was found higher frequency of the haplotype 455G/148T for the FGB -455G>A and FGB -148 C>T polymorphisms in women with primary RPL.
105

"Fibrinogênio como marcador de trombose" / Fibrinogen in the prediction of thrombosis

Almeida, Maria Antônia Campos 25 May 2006 (has links)
INTRODUÇÃO: Um grande número de estudos epidemiológicos têm demonstrado que o fibrinogênio é fator de risco consistente e independente para doença cardiovascular. O fibrinogênio, além de ser um determinante de trombose arterial foi considerado fator de risco de trombose venosa. Foram avaliados os níveis plasmáticos do fibrinogênio em indivíduos que apresentaram algum tipo de trombose não influenciada por reação de fase aguda ou resposta inflamatória. MÉTODOS: Neste estudo de caso-controle realizado entre julho de 2003 a abril de 2005 foram incluídos 39 pacientes, entre 25 e 65 anos, com diagnóstico objetivamente confirmado de trombose, sem antecedentes de neoplasia e colagenose. O tempo mínimo entre a evento e a coleta da amostra de sangue foi de 6 meses. O grupo controle foi constituído de doadores e funcionários voluntários do Hemocentro Regional de Juiz de Fora. A concentração plasmática de fibrinogênio e a medida da Proteína C Reativa foram realizados nos dois grupos. RESULTADOS:Os níveis médios de fibrinogênio foram significativamente maiores nos pacientes ( 316)que no grupo controle (259), p=0,0002. a média de idade foi 48,3 para os pacientes e 45,5 para o controle. A aplicação do teste qui quadrado demonstrou que não houve diferenças significativas nos grupos de pacientes e controles (30,8% e 27%, respectivamente) em relação ao tabagismo(pvalor = 0,72). A frequência de hipertensão foi significativamente maior no grupo de pacientes (28,2%) que no controle (5,4%) (p-valor=0,008). O teste t para a diferença dos níveis médios de fibrinogênio entre os grupos de trombose venosa e arterial não apresentou resultado estatisticamente significante (p-valor = 0,69). CONCLUSÃO: Com base nos dados deste estudo, os níveis de fibrinogênio estão relacionados com trombose, independente se arterial ou venosa. / INTRODUCTION: A great number of prospective epidemiologic studies have reported that fibrinogen is consistently and independently risk factor for the cardiovascular disease. The fibrinogen, a determinant of arterial thrombosis, was also considered a risk factor for the venous thrombosis. It was valued the fibrinogen plasmatic level in patients that had showed some kind of thrombosis event without influence by acute phase reactions or ongoing inflamatory responses. METHODS: In this cases-control study, fulfilled between july 2003 and april 2005, was included 39 patients, among 25 e 65 ears, with confirmed diagnosis of thrombosis and none neoplasis and collagenosis antecedent. Six months was the minimum time between event and blood sample collect. The control group was composed by blood donor and voluntary employee of the Hemocentro Regional de Juiz de Fora. The fibrinogen plasmatic concentration and the C-reactive proteins measure was made in both groups. RESULTS: The medium levels of fibrinogen were significantly higher in patients (316) than the control group (259), p=0,0002. The age average was 48,3 for the patients and 45,5 for the control. The “qui-quadrado" test application proved there wasn’t any significatives differences in both groups, patients (30,8%) and control (27%), in the relation with smoking (p-value = 0,72). The frequency of arterial hypertension was significantly higher in patient group (28,2%) than the control group (5,4%) (p-value = 0,008). The t-test for the differences of the fibrinogen average levels between venous and arterial thrombosis didn’t present any significant statistic result. CONCLUSION: Established in this research, the higher levels of fibrinogen are associated with thrombosis, independently if arterial or venous.
106

Effect of dietary fibre on selected haemostatic variables and C-reactive protein / C.J. North

North, C. J. (Christina Johanna) January 2006 (has links)
Thesis (Ph.D. (Nutrition))--North-West University, Potchefstroom Campus, 2007.
107

Local Delivery of Bisphosphonates from FibMat Matrix

Aronsson, Henrik January 2008 (has links)
Improving the functionality and reducing revision rates are important driving forces in the development of orthopaedic implants. FibMat is a fibrinogen based matrix developed towards commercialisation by the company Optovent AB. This matrix can be coated on implants and act as a local drug delivery system for bisphosphonates (BPs). BPs are drugs inhibiting bone resorption, and applied with FibMat to improve stability of implants in bone, e.g. when fixing bone fractures. In this thesis, FibMat loaded with BP (FibMat/BP) was coated on stainless-steel screws and titanium screws in order to investigate some technology properties relevant to its clinical applicability. Bone-mimicking materials were used to study scrape-off effect upon insertion. The coagulation properties of fibrinogen as well as the structural properties of BPs were studied after exposure to gamma radiation. The screws were coated with FibMat and BP (alendronate and 14C-alendronate) using standard coupling techniques. The total amount and distribution of BP after insertion was measured by liquid scintillation and autoradiography. Coagulation assays were performed in order to determine the coagulation properties of fibrinogen, exposed to doses up to 35 kGy, mixed with thrombin. The structural properties of four different BPs (alendronate, pamidronate, zoledronate and ibandronate), exposed to doses up to 35 kGy were analysed by transmission infrared spectroscopy. The results show that FibMat/BP coating on porous stainless-steel screws is virtually unaffected by insertion into bone materials. The anodised, planar titanium screws are more affected by the insertion process, but an even BP distribution in the cancellous material is indicated. The coagulation assays show that gamma-irradiated fibrinogen has a slower coagulation process compared to non-irradiated fibrinogen and form interrupted network unable to clot. The chemical structures of the BPs seem unaffected by exposure to gamma irradiation. In conclusion, the FibMat/BP is a promising technology for local distribution of BP in conjunction with bone implants.
108

Free oscillation rheometry monitoring of haemodilution and hypothermia and correction with fibrinogen and factor XIII concentrates

Winstedt, Dag, Tynngård, Nahreen, Olanders, Knut, Schott, Ulf January 2013 (has links)
Background Haemodilution and hypothermia induce coagulopathy separately, but their combined effect on coagulation has not been widely studied. Fibrinogen concentrate can correct dilutional coagulopathy and has an additional effect when combined with factor XIII concentrate. However, their effect on dilutional coagulopathy concomitant with hypothermia has not been studied previously. Free oscillation rheometry – FOR (Reorox®) – is a novel viscoelastic haemostatic assay that has not been studied in this context before. Methods Blood from 10 healthy volunteers was diluted by 33% with hydroxyethyl starch or Ringer’s acetate solutions. Effects of fibrinogen added in vitro with and without factor XIII were studied at 33°C and 37°C. Coagulation velocity (coagulation time) and clot strength (elasticity) were assessed with FOR. Coagulation was initiated in vitro with thromboplastin alone, or thromboplastin plus a platelet inhibitor. Results Hydroxyethyl starch increased the coagulation time and decreased clot strength significantly more than Ringer’s acetate solution, both in the presence and absence of a platelet inhibitor. There was a significant interaction between haemodilution with hydroxyethyl starch and hypothermia, resulting in increased coagulation time. After addition of fibrinogen, coagulation time shortened and elasticity increased, with the exception of fibrinogen-dependent clot strength (i.e., elasticity in the presence of a platelet inhibitor) after hydroxyethyl starch haemodilution. Factor XIII had an additional effect with fibrinogen on fibrinogen-dependent clot strength in blood diluted with Ringer’s acetate solution. Hypothermia did not influence any of the coagulation factor effects. Conclusions Both haemodilution and mild hypothermia impaired coagulation. Coagulopathy was more pronounced after haemodilution with hydroxyethyl starch than with Ringer’s acetate. Addition of fibrinogen with factor XIII was unable to reverse hydroxyethyl starch induced clot instability, but improved coagulation in blood diluted with Ringer’s acetate solution. Fibrinogen improved coagulation irrespective of hypothermia. / <p>Funding Agencies|Region Skane (Sweden)||CSL Beehring||</p>
109

Local Delivery of Bisphosphonates from FibMat Matrix

Aronsson, Henrik January 2008 (has links)
<p>Improving the functionality and reducing revision rates are important driving forces in the development of orthopaedic implants. FibMat is a fibrinogen based matrix developed towards commercialisation by the company Optovent AB. This matrix can be coated on implants and act as a local drug delivery system for bisphosphonates (BPs). BPs are drugs inhibiting bone resorption, and applied with FibMat to improve stability of implants in bone, e.g. when fixing bone fractures. In this thesis, FibMat loaded with BP (FibMat/BP) was coated on stainless-steel screws and titanium screws in order to investigate some technology properties relevant to its clinical applicability. Bone-mimicking materials were used to study scrape-off effect upon insertion. The coagulation properties of fibrinogen as well as the structural properties of BPs were studied after exposure to gamma radiation.</p><p>The screws were coated with FibMat and BP (alendronate and 14C-alendronate) using standard coupling techniques. The total amount and distribution of BP after insertion was measured by liquid scintillation and autoradiography. Coagulation assays were performed in order to determine the coagulation properties of fibrinogen, exposed to doses up to 35 kGy, mixed with thrombin. The structural properties of four different BPs (alendronate, pamidronate, zoledronate and ibandronate), exposed to doses up to 35 kGy were analysed by transmission infrared spectroscopy.</p><p>The results show that FibMat/BP coating on porous stainless-steel screws is virtually unaffected by insertion into bone materials. The anodised, planar titanium screws are more affected by the insertion process, but an even BP distribution in the cancellous material is indicated. The coagulation assays show that gamma-irradiated fibrinogen has a slower coagulation process compared to non-irradiated fibrinogen and form interrupted network unable to clot. The chemical structures of the BPs seem unaffected by exposure to gamma irradiation. In conclusion, the FibMat/BP is a promising technology for local distribution of BP in conjunction with bone implants.</p>
110

Effect of dietary fibre on selected haemostatic variables and C-reactive protein / Christina Johanna North

North, Christina Johanna January 2006 (has links)
Motivation: Cardiovascular heart disease (CVD) is the leading cause of death worldwide. Risk markers for CVD include, amongst others, the haemostatic factors tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor type 1 (PAI-1), factor VII (FVII) and fibrinogen and more recently, C-reactive protein (CRP), a sensitive marker of inflammation. Epidemiological studies have demonstrated an inverse association between dietary fibre (DF) consumption and risk factors for CVD and CVD prevalence. Some research indicates that this protection may be related to favourable changes in the haemostatic profile and inflammatory markers. This is applicable for the consumption of total DF, as well as soluble and insoluble fibre. However, clinical intervention trials report conflicting data on the effects of DF on t-PA, PAI-1, FVII, fibrinogen and CRP. In addition, available literature is not clear on the mechanisms through which DF may have favourable effects. Objective: The main objective of this study was to review the results of randomised controlled trials systematically on the effects of DF on the above-mentioned selected haemostatic variables and CRP in healthy adults and subjects with hypertriglyceridaemia and the metabolic syndrome. Methods: Human adult intervention trials, at least two weeks in duration, with an increased and measurable consumption of DF were included. Electronic databases were searched from the earliest record to May/July 2006 and supplemented by crosschecking reference lists of relevant publications. From the literature search, two reviewers identified studies that were rated for quality based on the published methodology. No formal statistical analysis was performed due to the large differences in the study designs of the dietary intervention trials. The primary outcome measures were percentage changes between intervention and control groups, or baseline to end comparisons for t-PA, PAI-1, FVII, fibrinogen and CRP. Results t-PA activity increased significantly (14-167%) over the short and long-term following increased fibre intakes. PAI-1 activity decreased significantly between 15-57% over periods ranging from two to six weeks. These favourable changes in t-PA and PAI-1 occurred in healthy, hypertriglyceridaemic and metabolic syndrome subjects following consumption of diets containing ≥3.3 g/MJ DF and ≥4.5 g/MJ DF respectively. Mechanisms through which DF may affect t-PA and PAI-1 include its lowering effect on insulinaemic and glycaemic responses, decreasing triglycerides which are a precursor of very-low-density lipoproteins, fermentation of DF to short-chain fatty acids, which may reduce free fatty acid concentrations, as well as the role of DF in promoting weight loss. High DF intakes did not have a significant effect on fibrinogen concentrations possibly because of relatively little weight loss, too low DF dosages and maintaining a good nutritional status. Inadequate study designs deterred from meaningful conclusions. Significant decreases in FVll coagulant activity (6-16%) were observed with DF intakes of ≥3.3 g/MJ and concomitant decreased saturated fat intakes and weight loss in healthy and hypertriglyceridaemic subjects. Confounding factors include weight loss and a simultaneous decreased intake of saturated fats. The type of fibre seems to play a role as well. Mechanisms through which DF may reduce FVll concentrations include its effects on triglyceride-rich lipoproteins, insulin and weight loss. Increased DF consumption with dosages ranging between 3.3-7.8 g/MJ were followed by significantly lower CRP concentrations (25-54%), however, simultaneous weight loss and altered fatty acid intakes were also present in all the studies. Mechanisms are inconclusive but may involve the effect of DF on weight loss, insulin, glucose, adiponectin, interleukin-6, free fatty acids and triglycerides. Conclusions: Epidemiological evidence indicates an association between DF and the CVD risk factors t-PA, PAI-1, FVII, fibrinogen and CRP. In general, the risk of CVD may improve with high-fibre intakes as indicated by the favourable changes in some of the parameters. However, simultaneous reduced fat intakes and weight loss presented difficulties in separating out the effects of specific components. Furthermore, DF is consumed in a variety of different forms and different dosages that may have different effects. Overall, the study designs used in the intervention trials prevented significant conclusions. DF did, however, play a role in modifying t-PA, PAI-1, FVII and CRP. Potential effects on fibrinogen were not quantifiable. Recommendations: The results from this investigation provide the motivation for additional controlled clinical research to establish the effect and mechanisms of DF on haemostatic variables and CRP. A critical aspect of future studies would be to set up suitable protocols. The amount of subjects, duration of the trials, confounding factors such as weight loss and altered fat intakes and differentiation between types and dosage of DF are important. DF supplemental studies are recommended as they may be the most suitable method to reach meaningful conclusions. / Thesis (Ph.D. (Nutrition))--North-West University, Potchefstroom Campus, 2007

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