Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2001. / Härtill 5 uppsatser.

Cerebral small vessel disease (SVD) is a leading cause of stroke and vascular dementia. The majority of cases are sporadic, occurring in the elderly hypertensive population. However, there also exist patients with familial disease. The most common form is Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL), caused by mutations in the NOTCH3 gene. In recent years, other genes have also been found to cause familial SVD, such as COL4A1/A2, HTRA1, FOXC1 and TREX1. Genome wide association studies (GWAS) have also revealed loci associated with sporadic SVD strokes and its related features. This thesis explores the genetic basis of SVD primarily from the angle of the 'one gene, one disease' hypothesis. We explore the phenotype of familial SVD using CADASIL as a prototype. We next adopt a candidate gene approach to rare variant discovery using high throughput sequencing (HTS) techniques in two forms: 1) a multi-gene sequencing panel to examine the presence of rare variants in a cohort of 993 presumed-sporadic, early-onset SVD stroke patients, and 2) whole genome sequencing in 118 pedigrees with suspected familial SVD. We also evaluate the prevalence of known disease-causing mutations in the general population using a cohort of whole genome sequenced non-SVD patients, and other control databases. We demonstrate that a few presumed-sporadic SVD stroke patients may in fact have familial disease that was not previously diagnosed. We show that known and novel rare variants in candidate genes are found in our cohort of familial SVD patients, and suggest a possible role for rare variants in genes associated with related phenotypes and sporadic disease in this cohort. Finally, we identify known disease-causing variants in relatively high frequencies in the population, and show that conclusions on the pathogenicity of variants based on allele frequency and functional analyses may sometimes be misguided, thus highlighting the current limitations we face in the clinical interpretation of variants identified on HTS. In recent years genetic studies have revealed that pathways in different familial diseases are likely to converge in the pathogenesis of sporadic disease. Further uncovering the genetic basis of undiagnosed cases of familial SVD may shed light on the mechanisms underlying the sporadic form of disease, and may in turn drive the identification of potential therapeutic targets.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2005. / Härtill 4 uppsatser.

Thesis (MScMedSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Please see fulltext for abstract / AFRIKAANSE OPSOMMING: Parkinson se siekte ( PD ) is 'n toenemend algemene neurodegeneratiewe siekte wat die progressiewe verlies van dopaminergiese neurone in die substantia nigra pars compacta behels, wat lei tot die ontwrigting van die motororiese senuweestelsel. ’n Neuronale verlies van meer as 50% van die normale vlakke is nodig vir die ontwikkeling van die kliniese simptome, insluitende bewing, spier rigiditeit, bradykinesia, en posturale onstabiliteit. Alhoewel beskikbare medikasies vir PD wel simptome onderdruk, is dit nie in staat om die siekte te voorkom of vordering daarvan te verhoed nie. Een van die mees bedeidende risikofaktore vir PD is toenemende ouderdom. Huidige epidemiologiese studies voorspel ‘n toename in populasie ouderdom wat belangrike implikasies vir die voorkoms van PD kan inhou. Die molekulere meganismes onderliggend aan die neurale agteruitgang in PD is steeds onbekend, maar dit blyk dat ‘n aantal genetiese faktore (in kombinasie met omgewingsfaktore) bydra tot die komplekse patogeniese agteruitgang van die siekte. Agt bevestigde gene is gevind om direk betrokke te wees by die etiologie van PD, naamlik: parkin, PINK1, DJ-1, ATP13A2, SNCA, LRRK2, VPS35, en EIF4G1. Hierdie gene is oorwegend geïdentifiseer en bestudeer in die Europese, Noord-Amerikaanse en Asiatiese bevolkings; terwyl die bestudering van Sub -Sahara- Afrika (SSA) bevolkings, veral dié van Swart Afrika afkoms, onderverteenwoordig bly in genetiese studies. Siende dat resultate verkry vanaf ander bevolkings nie verwant is aan die SSA bevolking nie, en ook nie ‘n voorspelling van wereldwye toename van die siekte kan verteenwoordig nie, is dit van belang dat omvattende genetiese studies uitgevoer word op hierdie onderbestudeerde bevolkings van SSA. Desnieteenstaande, die doel van die studie was om die molekulere etiologie van PD in ‘n groep Swart Suid-Afrikaanse (SA) PD pasiente te ondersoek. ‘n Totaal van 47 pasiente is gewerf vir die studie waarvan 26% ‘n famielie geskiedenis het vir die afwyking. Die gemiddelde ouderdom van aanvang vir die pasiente was 55.3 ± 11.2 jaar. Mutasie volgorderbepaling vir alle bekende PD gene is uitgevoer. Addisionele mutasie volgorderbepaling vir die GBA is ook uitgevoer siende dat heterosigotiese mutasies in die geen dien as ‘n sterk risikofaktor vir die ontwikkeling van PD. ‘n Verskeidenheid mutasie volgordebepalingstegnieke is geinkorporeer vir die studie, naamlik: Sanger volgordebepaling en hoë resolusie smelt tegniek (vir die identifisering van missense mutasies asook kleinskaalse invoegings of weglatings), en multiplex-afbinding afhanklike ondersoek versterkingstoets (vir die opsporing van veranderinge in kopiegetal). Verder is volgende generasie volgordebepaling gebruik vir die sistematiese ondersoek van die bekende PD gene, asook vir 160 kandidaat gene wat vooraf bepaal is. Fluoreserend-geetiketeerde polymerase ketting reaksie primers is gebruik vir genotipering van CAG herhalings uitbreidings in die ataxin-2 (SCA2) en die ataxin-7 (SCA7) gene, gevolg deur elektroforese met behulp van die “ABI 3130x1 Genetic Analyzer”. Mutasie volgordebepaling het voor die lig gebring dat die bekende PD gene klaarblyklik nie ‘n beduidende oorsaaklike rol speel in die patogenese van die siekte in die huidige groep Swart SA pasiente nie, want slegs 2 uit die 47 (43%) pasiente koester mutasies in parkin. Een van die pasiente besit ‘n heterosigotiese duplikasie van ekson 2 en ‘n heterosigotiese weglating van ekson 9; in die ander pasient is ‘n heterosigotiese ekson 4 weglating en ‘n heterosigotiese G430D mutasie geïdentifiseer. Verder is ‘n Q311K verandering in parkin gevind asook vier nuwe variante (I610T, H1758P, N2133S en T2423S) in die LRRK2 geen. Die patogenisiteit van hierdie variante moet egter nog bepaal word. Geen patogeniese herhaalings uitbreidings is gevind in die SCA2 en SCA7 lokusse nie, en die moontlikheid van die twee spinocerebellar ataksie subtipes as genetiese bepalers vir PD is uitgekanselleer. Geen patogeniese mutasies is gevind in enige van die oorblywende bekende PD gene nie, dit is dus waarskeinlik dat die pasiente wel mutasies in nuwe PD-geassosieerde gene besit. Hierdie is die eerste molekulere genetiese studie uitgevoer op uitsluitlik Swart SA PD pasiente, en ook die eerste omvattende ondersoek van al die bekende PD gene in ‘n SSA bevolking. Die algemene patogeniese mutasies in gene, wat voorheen bewys is as siekte veroorsakend in ‘n aantal Europese bevolkings, is nie bespeur in die huidige studie nie en kan dus nie verantwoordelik gehou word vir die voorkoms van PD in hierdie pasiente nie. Maar, siende dat die steekproefgrootte in hierdie studie relatief klein was, kan addisionele volgordebepaling van ‘n groter pasient groep voordelig wees in die bepaal van nuwe siekte-veroorsakende gene wat die potensiaal het om huidige hipoteses, dat die genetiese etiologie van PD duidelik verskil oor verskeie etniese groepe wereldwyd, te weerlê of bevestig. Die voortsetting van genetiese ondersoeke onder hierdie groep pasiente kan bydra tot insig met betrekking tot bevolking-spesifieke genetiese bepalers, en uiteindelik tot die identifisering van nuwe teikens vir medikasies teen die siekte.

The gastro-intestinal (GI) tract represents the largest surface of the body and is continuously exposed to the microbial environment. In such anatomy, the survival of the host requires that the intestinal microbial flora be contained without excessive immune-reactivity to commensal bacteria while retaining the ability to respond to episodic pathogens. The discriminative recognition between beneficial commensal bacteria and potentially harmful pathogens demands an accurate interpretation by the GI mucosal immune system. Any defects in the processes of innate immune recognition and killing may lead to the development and perpetuation of chronic intestinal inflammation, namely inflammatory bowel disease (i.e. Crohn's disease (CD) and ulcerative colitis (UC)) and post-infectious irritable bowel syndrome (PI-IBS). The aim of ours studies was to evaluate the contribution of candidate genes, involved in the homeostasis and regulation of the intestinal innate immune response, to the susceptibility to CD, DC, and PI-IBS. In the first phase, we describe functional and genetic association results supporting NLRP3, encoding NALP3/cryopyrin, as a novel CD susceptibility gene. We subsequently report that the MEFV gene, encoding pyrin, known to interact with and be involved in the same pathway as NALP3/cryopyrin, does not contribute to CD and DC susceptibility. No CD or DC additional associations were observed upon NLRP3-MEFV gene-gene interaction analyses. In the third phase, we report the first association study evaluating genetic determinants for PI-IBS, using the well-characterized Walkerton population cohort. We uncovered variants in the TLR9, CDH1, and IL6 regions associated with PI-IBS susceptibility. These results are in keeping with the pathophysiologic changes observed in patients with PI-IBS, which include increased intestinal permeability and intestinal immune activation. / Overall, these results contribute to a better understanding of the genetic susceptibility to CD, DC and PI-IBS and shed light on new pathogenic signaling pathways in the development of these diseases.

Abstract In this study, associations between periodontitis expression, serum levels of inflammatory markers and genetic factors were investigated. The periodontal status of 56 subjects with chronic periodontitis, 28 control subjects and 80 subjects with type I diabetes mellitus (DM) was examined. In addition, a reference group (n=178) with genetic but not with periodontal health data was included. The single nucleotide polymorphisms of CD14 -260, IL-6 -174, TNF-α -308, IL-10 -1082, IL-1A -889, IL-1B +3954, and TLR4 +896 were determined using PCR with RFLP or allele-specific primers, and comparisons of the genotype frequencies were made between the study groups and reference subjects. The serum concentrations of IL-6 and sCD14 were assayed using ELISA. The distributions of all the studied genotypes were similar in the periodontitis and the reference subjects. However, in the periodontitis group, the carriage of the T-containing genotype of the CD14 -260 and the GG genotype of the IL-6 -174 associated significantly with the extent of periodontitis, indicating that genetic factors play a role in the pathogenesis of the disease. Both the extent of periodontal infection and the IL-6 -174 genotype were significant determinants for the serum IL-6 level, subjects carrying the GG genotype having significantly higher serum IL-6 levels than those carrying the CC/CG genotype. The serum level of sCD14 was significantly higher in subjects carrying the T-containing than the CC genotype of the CD14 -260 in the control group but not in the periodontitis group, suggesting that severe periodontal infection overshadows the influence of the genotype on serum sCD14 level. Overall, the serum studies indicated that periodontal infection is associated with a low-grade systemic inflammatory response. Type 1 DM subjects carrying the GG genotype of the IL-6 -174 had a higher extent of periodontitis when compared with those carrying the CG/CC genotype. Our results also suggest that the IL-6 -174 genotype is a more significant determinant of the extent of periodontitis in type 1 DM than glycemic control.

No description available.

Hypoxia inducible factor-1α (HIF-1α) plays a critical role in the oxygen homeostasis of all metazoans. HIF-1α is a master transcriptional regulator which coordinates the adaptive response to low oxygen tension. Through activation of a plethora of downstream target genes, HIF-1α facilitates oxygenation by promoting angiogenesis and blood vessel dilation, in addition to modulating metabolic pathways to inhibit oxidative phosphorylation and promote glycolytic energy production. Given the critical roles of hypoxia, insufficient blood supply and perturbed energetics in the pathogenesis of cardiovascular disorders, notably ischaemic heart disease, therapeutic modulation of HIF-1α is of significant clinical interest. Previous studies have demonstrated an acute cardioprotective role for both endogenous and supraphysiological HIF-1α signalling in the context of myocardial ischaemia. In contrast, chronic supraphysiological HIF-1α activation in the unstressed heart has been shown to induce cardiac dysfunction. To address the effect of chronic endogenous HIF-1α activation post-myocardial infarction (MI), the present work employed a murine coronary artery ligation (CAL) model in conjunction with temporally-inducible, cardiac-specific deletion of Hif-1α. While CAL surgery successfully modelled myocardial infarction – eliciting substantial adverse cardiac remodelling and contractile dysfunction – there was no evidence of chronic HIF-1α activation by CAL in HIF knockout or control left ventricular samples. In keeping with this, chronic ablation of Hif-1α (from 2 weeks post-CAL) had no discernible additional effect upon cardiac function. Overall, these findings do not support a potential therapeutic role for inhibition of HIF-1α signalling in the chronic phase post-MI. The fundamental tricarboxylic acid (TCA) cycle enzyme fumarate hydratase (FH) converts fumarate to malate. FH deficiency is associated with smooth muscle and kidney tumours which exhibit normoxic HIF signalling due to fumarate accumulation. To investigate the potential for fumarate accumulation to elicit protective HIF signalling, a cardiac-specific Fh1 null mouse was developed through Cre-loxP recombination. Strikingly, despite interruption of the TCA cycle in a highly metabolically demanding organ, cardiac Fh1 null mice were viable, fertile and survived into adulthood, demonstrating the remarkable metabolic plasticity of the heart. However, by 3-4 months Fh1 null mice develop a lethal cardiomyopathy characterised by cardiac hypertrophy, ventricular dilatation and contractile dysfunction. Despite lack of a pseudohypoxic response, Fh1 null hearts did exhibit another phenomenon observed in FH-deficient cancers and also attributed to fumarate accumulation – activation of the nuclear factor (erythroid-derived 2)-like 2 (NRF2) antioxidant pathway. Heterozygous, but not homozygous, somatic deletion of Nrf2 extended the life expectancy of cardiac Fh1 null mice. Exploration of redox status revealed a more reductive environment in Fh1 null hearts than controls. As a corollary, inhibition of the rate limiting enzyme of the pentose phosphate pathway – a major source of cellular reducing equivalents – with dehydroepiandrosterone conferred striking amelioration of the Fh1 null cardiomyopathy, suggesting a possible pathogenic role for reductive stress. While loss of mitochondrial Fh1 activity and subsequent TCA cycle dysfunction likely contribute to the Fh1 null phenotype, the importance of cytosolic FH was unclear. To clarify this, FH was expressed specifically in the cytosol in vivo. This was sufficient to substantially rescue the Fh1 null cardiomyopathy, supporting a role for cytosolic FH disruption in its pathogenesis. Taken together, these findings highlight the potential for reductive stress to contribute to cardiac dysfunction and suggest a function for cytosolic FH in cardiac metabolic homeostasis.