OBJETIVO: A via metabólica da lipoproteína de baixa densidade (LDL) em pacientes com lúpus eritematoso sistêmico (LES) em uso de difosfato de cloroquina (DFC) foi avaliada através do comportamento cinético de uma nanoemulsão radioativa rica em colesterol (LDE) que se assemelha à estrutura lipídica da LDL. MÉTODOS: LDE foi marcada com 14C-colesterol éster (14C-CE), sendo a seguir injetada endovenosamente em pacientes do sexo feminino com LES inativo: 10 tomando DFC (grupo DFC), 10 sem tratamento (grupo SEM TRATAMENTO); e 10 mulheres normais (grupo CONTROLE). Os grupos foram pareados pela idade e seguiram rigorosos critérios de seleção de condições que pudessem interferir no perfil lipídico. Amostras de sangue foram coletadas em intervalos pré-estabelecidos após a infusão para mensuração da radioatividade. Níveis séricos de jejum de lipoproteínas foram determinados no início dos estudos cinéticos. RESULTADOS: Idade e índice de massa corpórea (IMC) foram similares nos grupos estudados. A taxa fracional de remoção (TFR) de 14C-CE foi significativamente maior no grupo DFC comparada ao grupo SEM TRATAMENTO (0,076 ± 0,037 vs. 0,046 ± 0,021 h-1; p < 0,05) e CONTROLE (0,0516 ± 0,0125 h-1; p < 0,05). Em concordância, níveis significativamente menores de colesterol total e LDL foram observados no grupo DFC (156 ± 16 e 88 ± 16 mg/dl) comparando-se com SEM TRATAMENTO (174 ± 15 e 108 ± 17 mg/dl; p < 0,05) e CONTROLE (200 ± 24 e 118 ± 23 mg/dl; p < 0,05). Além disso, o incremento em 50% na TFR de 14C-CE no grupo DFC foi acompanhado por uma redução em 20% no LDL-C comparando-se a SEM TRATAMENTO. CONCLUSÃO: Esta é a primeira demonstração in vivo que a remoção de LDE do plasma encontra-se aumentada em pacientes com LES em uso de DFC. Estes dados suportam o benefício desta droga no tratamento do LES e identificam o receptor de LDL como um mecanismo promissor de DFC na redução de lípides em pacientes tomando corticosteróides. / OBJECTIVE: Low-density lipoprotein (LDL) pathway in systhemic lupus erythematosus (SLE) patients taking chloroquine diphosphate (CDP) was evaluated through the kinetic behavior of a radioactive cholesterol-rich nanoemulsion (LDE) that resembles the LDL lipidic structure. METHODS: LDE was labeled with 14C-cholesteryl ester (14C-CE), then IV injected in inactive female SLE patients: 10 taking CDP (CDP), 10 without therapy (NO THERAPY); and 10 normal subjects (CONTROL). Groups were age-matched and followed rigorous selection criteria of conditions that interfere in the lipid profile. Blood samples were collected in pre-established intervals after infusion for radioactivity measurement. Fasting lipoproteins were determined in the beginning of kinetic studies. RESULTS: Age and body mass index (BMI) were similar in the studied groups. Fractional clearance rate (FCR) of 14C-CE was significantly greater in CDP compared to NO THERAPY (0.076 ± 0.037 vs. 0.046 ± 0.021 h-1; p < 0.05) and CONTROL (0.0516 ± 0.0125 h-1; p < 0.05). Accordingly, a significant lower total and LDL cholesterol were observed in CDP (156 ± 16 and 88 ± 16 mg/dl) compared to NO THERAPY (174 ± 15 and 108 ± 17 mg/dl; p<0.05) and CONTROL (200 ± 24 and 118 ± 23 mg/dl; p < 0.05). Moreover, the 50% increase in 14C-CE FCR in CDP was paralleled by 20% decrease in LDL-c compared to NO THERAPY. CONCLUSION: This is the first in vivo demonstration that removal of LDE from plasma was increased in SLE patients taking CDP. These data support its beneficial use in SLE and identify the LDL receptor as a promising CDP mechanism for lowering lipids in patients taking corticosteroids.

Diss. (sammanfattning) Umeå : Univ., 2007. / Härtill 4 uppsatser.

Call number: LD2668 .T4 1985 S22 / Master of Science

Abdominal aortic aneurysm (AAA) is a devastating disease that exhibits permanent lumen expansion typically in the infrarenal aorta. AAA is prevalent among aged population, especially in males. Despite the incidence in women is lower, studies indicate the tortuosity is more severe and aortic rupture risk is higher in women. In most patients, AAA remains asymptomatic until it ruptures leading to sudden and fatal hemorrhage. To date, there is no proven medical therapy that can prevent the expansion or rupture. Human observational studies implicate the presence of AAA is associated with both high plasma low-density lipoprotein-cholesterol (HDL-C) and low plasma high-density lipoprotein-cholesterol (HDL-C) concentrations. To examine the role of specific lipoproteins in development of AAA, angiotensin (Ang) II-induced AAA was firstly determined in apolipoprotein AI deficient (apoAI -/-) mice in both C57BL/6 and LDL receptor deficient (LDL receptor -/-) backgrounds. The deletion of apoAI led to a significant decrease of HDL-C concentrations. However, we were unable to define any exacerbation of AngII-induced AAA in either normo- or hyperlipidemic mice with apoAI deficiency. Next we compared AngII-induced AAA formation using multiple mouse strains with dietary manipulation to generate different severities of hypercholesterolemia. We demonstrated the apolipoprotein B (apoB)-containing lipoproteins promoted the development of AngII-induced AAA. Moreover, ezetimibe administration significantly reduced both apoB-containing lipoproteins and AAA formation. Together, our studies demonstrate that elevated apoB-containing lipoproteins, contribute to the development of AngII-induced AAA. To investigate the role of apoB-containing lipoproteins on established AAA, male LDL receptors -/- mice fed a Western diet were infused with AngII for 4 weeks to induced AAA. Then mice with AAA were stratified into either a group maintained on western diet or switched to a normal diet. AngII infusion was continued for an additional 8 weeks. The diet switch resulted in significantly reduced plasma cholesterol concentrations, which was attributable to the decrease of apoB-containing lipoproteins. We found a profound inhibition of aneurysm progression in diet switched mice associated with attenuated macrophage accumulation and medial thickening. Collectively, our data demonstrate that apoB-containing lipoproteins promote the progression of established AAA.

Assignment (MMed)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: Lipoprotein X (LpX) is an abnormal cholesterol-containing particle that may be present in the serum of subjects with cholestasis, lecithin:cholesterol acyltransferase (LCAT) deficiency and parenteral nutrition. The biochemistry, metabolism, clinical significance and laboratory analysis of LpX is discussed in this study. This laboratory-based project investigated icteric samples received at the Chemical Pathology laboratory, Tygerberg Hospital, for serum predictors of LpX and the use of a modified non-denaturing polyacrylamide gradient gel electrophoresis system in the detection of LpX. The study showed that the non-denaturing polyacrylamide gradient gel electrophoresis system (2-8%) is a useful test in demonstrating LpX in icteric plasma and has potential for a screening test in LCAT deficiency. Serum concentration of conjugated bilirubin, alkaline phosphatase, gamma glutamyltransferase, free cholesterol, phospholipid, free cholesterol: total cholesterol ratio and conjugated bilirubin: total bilirubin ratio are all good predictors of LpX. The ratio of free cholesterol to total cholesterol (FC/TC > 0.6) was the best predictor of LpX. In the setting of obstructive liver disease LpX is seen in 66% of patients if total cholesterol is > 7.5 mmol/L. / AFRIKAANSE OPSOMMING: Lipoproteien X (LpX) is ‘n abnormale cholesterol-bevattende partikel wat teenwoordig mag wees in die serum van persone met cholestase, lesitien:cholesterol asieltransferase (LCAT) gebrek en parenterale voeding. Die biochemie, metabolisme, kliniese belang en laboratorium analise van LpX word bespreek in hierdie werkstuk. Hierdie laboratorium-gebaseerde projek het geelsugtige monsters ondersoek wat ontvang is by die Chemiese Patologie laboratorium, Tygerberg Hospitaal, vir serum voorspellers van LpX en die gebruik van ‘n gemodifiseerde nie-denaturerende polie-akrielamied gradiënt gel elektroforese sisteem in die demonstrasie van LpX. Die bevindinge was dat die nie-denaturerende polie-akrielamied gradient gel elektroforese sisteem (2-8%) is ‘n nuttige toets om LpX te demonstreer in geelsugtige plasma en het potensiaal as ‘n siftingstoets in LCAT gebrek. Serum konsentrasie van gekonjugeerde bilirubien, alkaliese fosfatase, gamma glutamieltransferase, vry cholesterol, fosfolipied, vry cholesterol:totale cholesterol verhouding en gekonjugeerde bilirubien:totale bilirubien verhouding is alles goeie voorspellers van LpX. Die verhouding van vry cholesterol tot totale cholesterol (VC/TC > 0.6) was die beste voorspeller van LpX. In gevalle van obstruktiewe lewersiekte word LpX gesien in 66% van pasiente as die totale cholesterol meer as 7.5 mmol/l is.

Atherosclerosis is a disease of cardiovascular system and is usually located within large arteries. It is a major cause of death and mortality and it is related to over 12 million deaths annually affecting nearly all people in the modern world. It is a disease that involves the circulation of low density lipoproteins –LDLs (a main carrier of cholesterol) within the blood stream. These eventually accumulate in the cell wall of large and medium sized arteries to form plaques or atherosclerotic patches gradually narrow the lumen and gradually become the site of bleeding and thrombus formation. It is well known that atherosclerotic lesions in the arterial wall develop at certain sites in the human arterial system such as along the inner walls of curved segments and the outer walls of arterial bifurcations. This phenomenon is called the localization of atherosclerosis. As the early event leading to the genesis of atherosclerosis is the accumulation of atherogenic lipids such as low density lipoproteins (LDLs) within the arterial wall, mass transport between the blood and the artery wall must play an important role in the genesis and development of atherosclerosis. In the present study we investigate the correlation of luminal surface LDL concentration (cw) distribution with the distribution of wall shear stress (WSS) and the effects of both non – Newtonian behavior and pulsation of blood flow on the distributions of luminal surface LDL concentration along the wall of the human aorta. The dependence of viscosity and diffusivity and the local density are incorporated in the single and two phase flow models rendering these quantities position dependent. Then we compared the predictions of a single phase model with those of the two phases one under both steady flow and realistic pulsatile flow conditions using a human aorta model constructed from CT images. Then local hemodynamics studied by using computational fluid-dynamics (CFD) applied to realistic geometric model of the aorta. It is therefore important to solve the problem of accurately reconstructing geometric models from CT image in order to gain accuracy in CFD computations and predictions. The present numerical study revealed an adverse correlation between wall shear stress and the luminal surface LDL concentration in the aorta. The results indicate that the luminal surface LDL concentration depends not only on the local wall shear stress but also on both the global and local flow patterns. Also the results showed that under steady flow conditions, although the shear thinning non – Newtonian nature of blood could elevate wall shear stress (WSS) in most regions of the aorta, especially in areas with low wall shear stress, it had little effect on luminal surface LDL concentration (cw) in most regions of the aorta. Nevertheless, it could significantly enhance cw in areas with high luminal surface LDL concentration through the shear depended diffusivity of LDLs. The pulsation of blood flow could significantly reduce cw in these disturbed places. In conclusion the shear shining non – Newtonian nature of blood has little effect on LDL transport in most regions of the aorta, but in the atherogenic – prone areas where luminal surface LDL concentration is high its effect is apparent. Similar is the effect of pulsatile flow on the transport of LDLs. / Η αθηροσκλήρωση είναι μία νόσος του καρδιαγγειακού συστήματος και βρίσκεται συνήθως μέσα σε μεγάλες αρτηρίες. Πρόκειται για μια σημαντική αιτία θανάτου και η θνησιμότητα της σχετίζεται με πάνω από 12 εκατομμύρια θανάτους ετησίως, η οποία επηρεάζει σχεδόν όλους τους ανθρώπους στο σύγχρονο κόσμο. Είναι μια ασθένεια που περιλαμβάνει την κυκλοφορία των χαμηλής πυκνότητας λιποπρωτεϊνών-LDLs (ένας κύριος φορέας της χοληστερόλης) εντός της κυκλοφορίας του αίματος. Η χαμηλής πυκνότητας πρωτεΐνες συσσωρεύονται στο αρτηριακό τοίχωμα των μεγάλων και μεσαίου μεγέθους αρτηριών και σχηματίζουν πλάκες ή αθηρωματικά μπαλώματα, τα οποία σταδιακά προκαλούν στένωση του αυλού και έπειτα δημιουργείται αιμορραγία στη περιοχή, με αποτέλεσμα το σχηματισμό θρόμβων. Είναι γνωστό ότι οι αθηροσκληρωτικές βλάβες στο αρτηριακό τοίχωμα αναπτύσσονται σε συγκεκριμένες περιοχές στο ανθρώπινο αρτηριακό σύστημα, όπως κατά μήκος των εσωτερικών τοιχωμάτων των καμπυλωτών τμημάτων και των εξωτερικών τοιχωμάτων των αρτηριακών διακλαδώσεων. Αυτό το φαινόμενο ονομάζεται localization of atherosclerosis. Καθώς το πρώιμο συμβάν που οδηγεί στη γένεση της αθηροσκλήρωσης είναι η συσσώρευση των αθηρογόνων λιπιδίων όπως είναι οι λιποπρωτεΐνες χαμηλής πυκνότητας (LDLs) εντός του αρτηριακού τοιχώματος, η μεταφορά μάζας μεταξύ του αίματος και του τοιχώματος της αρτηρίας μάλλον διαδραματίζει σημαντικό ρόλο στην γένεση και την ανάπτυξη της αθηροσκλήρωσης . Στην παρούσα μελέτη διερευνάται η συσχέτιση της κατανομής της συγκέντρωσης των LDL (cw) στην επιφάνεια του αυλού με την κατανομή των διατμητικών τάσεων (WSS), καθώς και η επίδραση της μη - Νευτώνειας συμπεριφοράς και της παλμικής ροής του αίματος στις κατανομές της συγκέντρωσης των LDL στην επιφάνεια του αυλού κατά μήκος του τοιχώματος της ανθρώπινης αορτής. Η εξάρτηση του ιξώδους, της διάχυσης και της τοπικής πυκνότητας ενσωματώνονται στο μονοφασικό και το διφασικό μοντέλο ροής, καθιστώντας αυτές τις ποσότητες να εξαρτώνται από τη θέση. Στη συνέχεια, συγκρίνουμε τα αποτελέσματα του μονοφασικού μοντέλου με το διφασικό μοντέλο, τόσο υπό σταθερή ροή όσο και υπό ρεαλιστικές συνθήκες παλμικής ροής, χρησιμοποιώντας ένα ανθρώπινο μοντέλο αορτής κατασκευασμένο από CT εικόνες. Τέλος, μελετάτε η τοπική αιμοδυναμική με τη χρήση υπολογιστικής ρευστοδυναμικής (CFD) που εφαρμόζεται στο ρεαλιστικό γεωμετρικό μοντέλο της αορτής. Επομένως, είναι σημαντικό να λύσουμε το πρόβλημα της ακρίβειας στην ανακατασκευή του γεωμετρικού μοντέλου από την εικόνα CT, προκειμένου να έχουμε ακρίβεια στους CFD υπολογισμούς και στα αποτελέσματα. Η παρούσα αριθμητική μελέτη έδειξε ένα αντίστροφο συσχετισμό μεταξύ της διατμητικής τάσης του τοιχώματος και της συγκέντρωσης των LDL στην επιφάνεια του αυλού στην αορτή. Τα αποτελέσματα, επίσης έδειξαν ότι η συγκέντρωση των LDL στην επιφάνεια του αυλού εξαρτάται όχι μόνο από την τοπική διατμητική τάση του τοιχώματος αλλά από τα ολικά και τοπικά πρότυπα ροής. Επίσης, τα αποτελέσματα έδειξαν ότι κάτω από συνθήκες σταθερής ροής, η μη - Νευτώνεια φύση του αίματος αυξάνει τη διατμητική τάση του τοιχώματος (WSS) στις περισσότερες περιοχές της αορτής, ιδιαίτερα στις περιοχές με χαμηλή διατμητική τάση και έχει μικρή επίδραση στη συγκέντρωση των LDL (cw) στην επιφάνεια του αυλού, στις περισσότερες περιοχές της αορτής. Παρ 'όλα αυτά, μπορεί να ενισχύσει σημαντικά το cw στις περιοχές με υψηλή συγκέντρωση των LDL στην επιφάνεια του αυλού μέσω της εξαρτώμενης διατμητικής διάχυσης των LDLs. Η παλμικότητα της ροή του αίματος μπορεί να μειώσει σημαντικά το cw σε αυτές τις διαταραγμένες θέσεις. Εν κατακλείδι, η μη - Νευτώνεια συμπεριφορά του αίματος έχει μικρή επίδραση στη μεταφορά των LDL στις περισσότερες περιοχές της αορτής, αλλά στις αθηρογόνες - επιρρεπείς περιοχές όπου η συγκέντρωση LDL στην επιφάνεια του αυλού είναι υψηλή τα αποτελέσματα είναι εμφανή. Παρόμοια είναι η επίδραση της παλμικής ροής στη μεταφορά των LDLs.

published_or_final_version / Chemistry / Master / Master of Philosophy

Two studies were conducted to determine how HDL cholesteryl ester and apoprotein catabolism might contribute to the observed hypercholesterolemia of copper-deficient rats. Weanling male Sprague-Dawley rats were divided into two dietary treatments; copper-adequate (control, 5-7 mg Cu/kg diet) and copper-deficient (0.6-0.8 mg Cu/kg diet). Deionized water and diet were provided ad libitum. Dietary copper deficiency resulted in enlarged intravascular pools of HDL cholesteryl esters and total protein. HDL were isolated from rats of both treatment groups, radiolabeled, and injected into animals of the respective groups. In Study I, HDL apoproteins were labeled by iodination, whereas HDL in Study II were doubly labeled by additionally incorporating into the particle core [³H]cholesteryl linoleyl ether, which served as a nondegradable analog of HDL cholesteryl ester. At specific time intervals up to 12 hours after injection, blood and tissue samples were removed and analyzed for radioactivity. Plasma disappearance curves indicated that HDL cholesteryl esters were preferentially catabolized 1.6-fold faster than HDL protein in controls and 2.5-fold faster in copper-deficient animals. Clearance of individual apoproteins did not occur at significantly different rates in either treatment group. Absolute mass removal of HDL cholesteryl ester and total protein from the plasma was significantly increased in copper-deficient rats. Virtually all of the increased removal of HDL cholesteryl ester was attributed to the liver, whereas most of the increased uptake of HDL protein was attributed to the bulk tissues and not the liver. Since previous studies indicate that copper deficiency may not result in increased cholesterol excretion, these data suggest that cholesteryl esters delivered to the liver of copper-deficient rats are possibly reassembled into new HDL particles at an increased rate. The observed hypercholesterolemia in this animal model, then, appears to be the result of an imbalance in the net flux of cholesterol between the tissues and the plasma.

Two studies were designed to investigate the time course development of enlarged plasma volume and cholesterol pool size in copper (Cu)-deficient rats as well as influence of Cu deficiency on the lipid composition of lipoproteins. Rats were randomly assigned to three dietary Cu treatments (deficient, marginal, and adequate) in the Study I and two dietary Cu treatments (deficient and adequate) in Study II. Enlargement of plasma volume and cholesterol pool size were established prior to the increase in plasma cholesterol concentration. Cu concentration was decreased, whereas iron and zinc concentrations were increased in the organs of Cu-deficient and Cu-marginal rats. The plasma pool size of VLDL triglyceride was elevated 6-fold, protein and phospholipid were unaltered, and cholesterol was reduced 36%. The plasma pool size of lipid and protein components of HDL and LDL fractions were markedly elevated in Cu-deficient rats.

Genetic polymorphism of apolipoprotein (apo) E has been shown to account for a significant amount of variance in plasma lipid and lipoprotein levels, thereby contributing to the incidence of cardiovascular disease across populations. In this cross-sectional study apo E genotypes were determined in a sample of 173 healthy, middle-aged Indian women using a restriction isotyping method, in which DNA was amplified by PCR and the Cfol restricted DNA fragments were separated on a polyacrylamide gel, allowing unambiguous typing of the common apo E genotypes. Considering the three common alleles, e2, e3 and e4, a reduced frequency of the e2 allele was observed in the study population in comparison to other populations around the world. This finding underlines the heterogeneity of apo E allele frequencies in different populations. This study also investigated possible effects of apo E genotype on lipoprotein changes in this sample of women spanning the menopause. Apo E polymorphism was associated with significant differences in plasma lipid levels. Notably, total and low density lipoprotein cholesterol and more especially plasma triglyceride concentrations were increased in carriers of the e3/4 genotype. Two-way analysis of variance of the effect of apo E genotype and menopausal status on the lipid profile showed no significant interaction effect, indicating that the effects of apo E genotype on the lipid profile do not differ significantly between premenopausal and postmenopausal women. Age and to a lesser extent the waist hip ratio also correlated with lipid concentrations, but menopausal status had no apparent effect in this sample. This study confirms the potentially deleterious effect of the e4 allele, in a vulnerable population. The reduced occurrence of the E2 isoform, which is considered to offer a measure of protection against cardiovascular disease, may contribute to the relatively high incidence of coronary heart disease in the South African Indian population. However, the relatively low incidence of the e2 allele may protect this population against the occurrence of type III hyperlipoproteinaemia precipitated by diabetes and obesity in e2/2 homozygotes. / Thesis (M.Med.)-University of Natal, Durban, 1993.