Cirrhosis is a leading cause of death in the United States and has severe and costly complications. Because of the clinical significance of cirrhosis, it is important that noninvasive methods be developed to detect cirrhosis early and to monitor its progression with advancing liver disease. Previous studies on portal venous hemodynamics have been performed mainly with ultrasound with mixed results. Magnetic Resonance Imaging offers several advantages over ultrasound including acquisition of both high quality anatomical and hemodynamic information. Phase-Contrast MR was used to gather velocity data for the portal venous system. Methods were developed to perform registration, segmentation and isolation of the portal vein geometries and velocity data. Computational Fluid Dynamics was also employed to further investigate the flow within the portal vein. Velocity data for the portal vein, superior mesenteric vein, splenic vein and the right or left portal vein was acquired in varying numbers for both data sets. Even with the limited number of subjects a few parameters were significant. Patients with cirrhosis had a significantly increased portal vein area and a significantly decreased average velocity per liver volume and velocity variance. Patients with cirrhosis had a significantly increased splenic vein area and average flow rate per liver volume. While these results are preliminary due to small sample size, they are promising and require further investigation and more subjects including varying stages of disease.

submitted by Liu Dan. / Thesis (M.Sc.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 66-80). / Abstract also in Chinese. / CONTENTS --- p.i / LIST OF TABLES --- p.iii / LIST OF FIGURES --- p.iv / LIST OF ABBREVIATIONS --- p.v / ACKNOWLEDGEMENTS --- p.vi / ABSTRACT --- p.vii / Chapter Chapter 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- History --- p.1 / Chapter 1.2 --- Immunoglobulins --- p.3 / Chapter 1.2.1 --- Structure --- p.3 / Chapter 1.2.2 --- Properties of immunoglobulins --- p.7 / Chapter 1.3 --- Monoclonal proteins and monoclonal gammopathies --- p.12 / Chapter 1.3.1 --- Monoclonal proteins --- p.12 / Chapter 1.3.2 --- Monoclonal gammopathies --- p.14 / Chapter 1.4 --- Laboratory investigation of monoclonal immunoglobulin --- p.17 / Chapter 1.4.1 --- The current procedure of investigation in laboratory --- p.17 / Chapter 1.4.2 --- Problems in identifying monoclonal immunolgobuin --- p.19 / Chapter 1.5 --- Comparison of different techniques --- p.20 / Chapter 1.5.1 --- Immunoelectrophoresis --- p.20 / Chapter 1.5.2 --- Immunofixation electrophoresis --- p.22 / Chapter 1.5.3 --- Isoelectric focusing and immunoisoelectric focusing --- p.24 / Chapter 1.6 --- Aim of the present study --- p.27 / Chapter 1.7 --- Design of experiment --- p.27 / Chapter Chapter 2 --- MATERIALS AND METHODS --- p.30 / Chapter 2.1 --- Study subjects --- p.30 / Chapter 2.2 --- Apparatus --- p.30 / Chapter 2.2 --- Apparatus --- p.30 / Chapter 2.3 --- Reagents and materials --- p.32 / Chapter 2.4 --- Preparation of gels --- p.35 / Chapter 2.5 --- Isoelectric focusing procedure --- p.36 / Chapter 2.6 --- Acid fixation and staining --- p.37 / Chapter 2.7 --- Technical factors affecting results --- p.38 / Chapter Chapter 3 --- RESULTS --- p.40 / Chapter 3.1 --- Interpretation of results in isoelectric focusing --- p.40 / Chapter 3.2 --- Affecting factors --- p.47 / Chapter 3.3 --- Comparison of the results between IEF and IFE --- p.53 / Chapter Chapter 4 --- DISCUSSION --- p.59 / Chapter Chapter 5 --- CONCLUSION --- p.65 / References --- p.66

The face of transplantation has changed in recent decades. The improvement can be observed not only in terms of survival, but also the improved quality of life after this demanding procedure. This is one of the reasons why quality of life is one of the factors to consider (Durant, 2019). This is also due to the fact that in today's modern society one does not only want to survive, but wants to live fully. He wants to benefit his family and the society in which he lives. He wants to do his hobbies. Everybody wants to be active physically and also mentally. Today, quality of life is considered an indicator suitable for assessing physical, mental and social health (Chrastina, 2015). Methodology: The aim of this work is to evaluate how patients after liver transplantation perceive different domains related to quality of life and whether the results are different depending on the time elapsed from transplantation. For the purposes of the research was chosen a quantitative method using a questionnaire. A standardized WHOQOL BREF was used. The questionnaire contains 24 closed questions, which contain four domains and two questions themselves. Two separate questions assess the overal quality of life and overall health. The questionnaire was supplemented by two questions, which were aimed at obtaining...

Acute Upper Gastrointestinal Bleeding (AUGIB) accounts for 7000 deaths in the UK annually and is the single leading indication for transfusion of blood components. A large UK audit in 2007 reported high case fatality and rates of further bleeding. Since many deaths are determined by pre-existing co-morbidity, strategies to improve outcome should be targeted at preventable deaths and therefore focus upon improved control of haemorrhage and prevention of further bleeding, which are investigated in this thesis. Data for the analyses presented originate from the UK national audit of AUGIB, a laboratory study and a cross sectional survey. Five broad themes were investigated including service provision and timing of endoscopy, the use of transcatheter arterial embolisation (TAE) or surgery for refractory bleeding, the impact of coagulopathy on outcome, management of acute variceal haemorrhage (AVH) and haemostatic derangements after AVH, and the use of red blood cells (RBCs). Although there was no evidence of a “weekend effect” for mortality, earlier endoscopy (<12 hours) was associated with improved control of haemorrhage in higher risk patients compared to later endoscopy (>24 hours). TAE was an effective and safe modality for refractory bleeding, but the high post-surgical mortality (29%) raises questions about the appropriateness of case selection for surgery. Coagulopathy after non-variceal haemorrhage was associated with a 5-fold increase in risk-adjusted mortality. Further bleeding after AVH was strikingly high (26%) with notable deficiencies in the use of vasopressors, antibiotics and endotherapy. Global assessments of coagulation demonstrated that thrombin generation after AVH was normal, but clot strength was poor with excessive fibrinolysis. Platelets, fibrinogen and antifibrinolytics improved haemostasis ex vivo but coagulation factor transfusion had no effect. RBC transfusion practice is variable. This work on AUGIB provides new data highlighting areas of sub-optimal care, and informs both current practice and research questions for new interventional trials.

No description available.

Thesis (PhD (Medicine. Internal Medicine))--Stellenbosch University, 2008. / Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease in Western countries, extending from steatosis (FLD) to steatohepatitis (NASH). Differentiation between NASH and nonprogressive NAFLD is difficult on clinical grounds therefore a need exists to identify reliable biomarkers of disease progression. The aims of the study were 1) to describe the disease profile of NAFLD/NASH in South African patients of the Western Cape, 2) to investigate the metabolic derangements associated with this condition, including insulin resistance, lipid abnormalities and liver fibrogenesis, and 3) to assess the possible involvement of candidate genes in relation to the disease phenotype in the patient cohort. A total of 233 patients (73% female) were enrolled in this study, consisting of 69% Cape Coloured, 25% Caucasian, 5% Black and 1% Asian individuals. All subjects were obese or overweight based on the assessment of body mass index (BMI). Screening for NAFLD identified 182 patients (87%) with ultrasonographical evidence of fatty infiltration and/or hepatomegaly. Liver biopsies were performed on patients with persistently abnormal liver functions and/or hepatomegaly. NAFLD was confirmed histologically in 111 patients of whom 36% had NASH and 17% advanced liver fibrosis. None of the Black patients had advanced fibrosis.

Ο σκοπός αυτής της μελέτης ήταν να διερευνηθεί η συχνότητα της εμφάνισης λοίμωξης σε ηπατοπαθείς, η καταγραφή των πιο συχνών λοιμώξεων σε αυτή την ομάδα ασθενών καθώς και η διερεύνηση της επίπτωσης της κίρρωσης στην κυτταρική τους ανοσία Επίσης, στόχος μας ήταν η διερεύνηση της παρουσίας των κυτοκινών στο ασκιτικό υγρό κιρρωτικών ασθενών με ή χωρίς αυτόματη βακτηριακή περιτονίτιδα (ΑΒΠ) και της επίδρασης της ΑΒΠ στην έκφραση των προφλεγμονωδών, αντιφλεγμονωδών κυτοκινών και των υποδοχέων τους στο ασκιτικό υγρό ΑΣΘΕΝΕΙΣ-ΜΕΘΟΔΟΙ: Η μελέτη περιέλαβε ασθενείς με κίρρωση του ήπατος, οποιασδήποτε αιτιολογίας, που εισήχθησαν στο νοσοκομείο από το Μάιο 2006 μέχρι τον Δεκέμβριο 2007. Από τους συνολικά 110 ασθενείς με κίρρωση, οι 67 (ομάδα 1, 59.1%) εισήχθησαν για διάφορους λόγους εκτός από λοίμωξη, οι 24 (ομάδα 2, 21.8%) παρουσίασαν σύνδρομο σήψης και οι 19 (ομάδα 3, 19.1%) παρουσίασαν κιρσορραγία. Σε όλους τους ασθενείς έγινε καταγραφή των δημογραφικών τους στοιχείων, του τύπου λοίμωξης και μετρήθηκαν οι Τ- λεμφοκυτταρικοί υποπληθυσμοί, δηλ. CD3, CD4, CD5, CD8, CD14, CD20, CD56, CD64 καθώς και ο λόγος CD4/CD8 με κυτταρομετρία ροής. Οι μετρήσεις στους ασθενείς των ομάδων 2 και 3 έγιναν κατά την ημέρα της εισαγωγής, την τρίτη ημέρα νοσηλείας και την ημέρα εξόδου. Στους ασθενείς της ομάδας 1, οι μετρήσεις έγιναν μόνο την ημέρα της εισαγωγής. Μελετήθηκαν επίσης και 30 υγιή άτομα της ίδιας εθνικότητας και με παρόμοια δημογραφικά χαρακτηριστικά με τους υπόλοιπους ασθενείς. Αυτοί δεν νοσηλέυθηκαν, δεν είχαν κανένα πρόβλημα υγείας ούτε είχαν μεταγγισθεί. Μελετήθηκαν επίσης χωριστά 13 κιρρωτικοί ασθενείς, από τους συνολικά 110, οι οποίοι είχαν ασκίτη και εισήχθησαν στο Νοσοκομείο κατά την ίδια περίοδο. Αυτοί διακρίθηκαν σε δυο ομάδες: ομάδα 1 : ασθενείς με ΑΒΠ , ομάδα 2: ασθενείς χωρίς ΑΒΠ. Μετρήθηκαν οι κυττοκίνες : IL-1b, IL-1RA, IL-6, IL-10, TGF-1b, TNF-a, STNFRI, STNFRII. Οι μετρήσεις έγιναν με μέθοδο ELISA. ΑΠΟΤΕΛΕΣΜΑΤΑ : Οι απόλυτες τιμές των ολικών Τ λεμφοκυττάρων (CD3), των βοηθητικών (CD4) λεμφοκυττάρων, των κατασταλτικών (CD8) λεμφοκυττάρων και των CD5 λεμφοκυττάρων είναι μικρότερες στις ομάδες των κιρρωτικών με λοίμωξη και κιρσορραγία. Ειδικότερα, στην ομάδα των κιρσορραγούντων κιρρωτικών οι διαφορές στα βοηθητικά λεμφοκύτταρα (CD4) και τα ολικά λεμφοκύτταρα (CD3) κατά την έξοδο από το νοσοκομείο ήταν στατιστικά σημαντικές (Ρ< 0,05), ενώ όχι στους σηπτικούς. Οι απόλυτες τιμές όλων των Τ λεμφοκυτταρικών υποπληθυσμών ήταν υψηλότερες κατά την εισαγωγή και μειώθηκαν κατά τη διάρκεια νοσηλείας. Οι διαφορές στο ποσοστό συνέκφρασης στους δείκτες CD14/CD64 των ουδετεροφίλων ήταν σημαντικά μειωμένο στους σηπτικούς.Οι τιμές των κυτοκινών IL-10, IL-6, TNF-a, IL-1RA, STNFRI, STNFRII ήταν υψηλότερες στους ασθενείς με ΑΒΠ. Στατιστικά σημαντικές διαφορές (Ρ<0,05) ανάμεσα στις δυο ομάδες παρατηρήθηκαν μόνο στις τιμές των STNFRII, IL-1RA (υψηλότερες στους ασθενείς με ΑΒΠ). Η IL-1β δεν ανιχνεύθηκε στο ασκιτικό υγρό καμίας ομάδας ασθενών .Οι τιμές του TGF-1b ήταν χαμηλότερες στους ασθενείς με ΑΒΠ. ΣΥΜΠΕΡΑΣΜΑΤΑ: Το σύνδρομο σήψης αποτελεί συχνό αίτιο εισαγωγής στο νοσοκομείο ασθενών με κίρρωση. Από τη βιβλιογραφία προκύπτει οτι 30-50% των κιρρωτικών έχουν βακτηριακη λοίμωξη κατά την εισαγωγή τους στο νοσοκομείο. Στη μελέτη αυτή φάνηκε ότι το 21.8% των κιρρωτικών εισάγονται στο νοσοκομείο λόγω λοίμωξης. Οι Τ λεμφοκυτταρικοί υποπληθυσμοί σε ασθενείς με σύνδρομο σήψης δεν διαφέρουν σημαντικά από τους αντίστοιχους ασθενών χωρίς σήψη. Αντίθετα, οι υποπληθυσμοί των βοηθητικών Τ λεμφοκυττάρων σε κιρρωτικούς με κιρσορραγία είναι σημαντικά μειωμένη. Φαίνεται λοιπόν οτι οι ασθενείς με κίρρωση και σήψη έχουν ικανοποιητική κυτταρική ανοσιακή απάντηση ενώ αυτό δεν ισχύει και για αυτούς με κιρσορραγία. Τα επίπεδα των φλεγμονωδών και ιδιαίτερα των αντιφλεγμονωδών κυτοκινών IL-1RA και sTNFRII στο ασκιτικό υγρό κιρρωτικών ασθενών είναι αυξημένα σε περίπτωση φλεγμονής του περιτοναίου. Η φλεγμονώδης απάντηση στη λοίμωξη, όπως φαίνεται από τα επίπεδα των κυτοκινών στο ασκιτικό υγρό, είναι αυξημένη στους κιρρωτικούς ασθενείς γενικά και ιδιαίτερα σε αυτούς που αναπτύσσουν αυτόματη βακτηριακή περιτονίτιδα. Ίσως υπάρχει συσχέτιση αυτής της διαπίστωσης με τη βαρύτητα της πρόγνωσης και τις σοβαρές αιμοδυναμικές διαταραχές που παρατηρούνται σε κιρρωτικούς με αυτόματη βακτηριακή περιτονίτιδα. / To identify the demographic characteristics of cirrhotic patients, the most frequent infections and the difference in lymphocyte subsets between cirrhotic patients with gastrointestinal bleeding, infection and other cirrhotic patients. We also tried to determine the pattern of cytokine expression in the ascitic fluid (AF) of cirrhotic patients either with or without spontaneous bacterial peritonitis and investigate the effects of SBP on some cytokines in ascitic fluid PATIENTS AND METHODS: We included 110 patients, who were admitted to hospital from May 2006 to December 2007. Patients were divided into three groups: group 1: including those who were admitted through any cause, group 2: patients with any type of infection and group 3: patients with gastrointestinal bleeding. We collected: demographic characteristics, etiology of cirrhosis, the cause of admission to hospital, the type and frequency of infection, and the mortality. We also measured absolute T lymphocyte subpopulations (CD3, CD56, CD4, CD8, CD5, CD20, CD14, CD64) using flow cytometry. Also, we studied 13 cirrhotic patients, who were admitted to the department of Internal Medicine of University Hospital of Patras within the same period for a variety of reasons. From the amount of patients, seven patients developed SBP (group 1) and six patients presented no evidence of infection, including SBP (group 2). Ascitic levels of IL-1b, TNF-a, IL-6, IL-10,a IL-1ra, STNFRI, STNFRII were assayed with ELISA kits. RESULTS: 21.8% developed any infection, 19.1 % had gastrointestinal bleeding and 59.1 % were admitted through any cause. The most frequent infections were: pulmonary tract infections (30.6%), spontaneous bacterial peritonitis (22.2%), gastrointestinal infections (13.9%) and urinary tract infections (8.3%). In 11.1% cases, the cause of infection was not identified. The mortality rate was 9%. We observed a significant decrease in absolute counts of total T lymphocyte subsets (CD3) between group 1 and 3 on Day 3. We also found significant decrease (P< 0.05) in T-helper lymphocytes (CD4) on Day 3 and exit day in these groups. For ascitic fluid measurements of the 13 patients, multivariate analysis showed significant differences (P< 0,05) between the two groups to the levels of STNFRII and IL-1RA. Ascitic levels of IL-10, IL-6, IL-1ra, TNF-a, STNFRII and STNFRI were higher (not statistical significant ) in the ascitic fluid of patients with SBP. However, TGF-b1 levels were lower in group 1 patients. It is remarkable that IL-1b was not expressed in patients either with or without spontaneous bacterial peritonitis. DISCUSSION: Sepsis is a common reason of admission to hospital. 30-50% of cirrhotic patients develop a type of infection upon admission to the hospital. In our study, 21.8% of patients were admitted to hospital with a type of infection. T-helper (CD4) and total (CD3) lymphocyte subsets were statistical significant lower (P<0,05) in patients with variceal bleeding. Probably, patients with gastrointestinal bleeding have defensive immune system. On the other hand, those with sepsis have satisfactory cellular immunity. Apart from that, we demonstrated an increased cytokine production in ascitic fluid of cirrhotic patients, while the levels of anti-inflammatory cytokines sTNFRII and IL-1ra are significantly increased in SBP. It seems, therefore, that an ascitic fluid anti-inflammatory response is characteristic in SBP, and this might compromise the final outcome.

narmq2@hotmail.com / Objetivo: La inflamación sistémica empeora los trastornos circulatorios en el paciente cirrótico y recientemente el síndrome de respuesta inflamatoria sistémica (SRIS) podría ser un indicador pronóstico en ellos. El objetivo del estudio fue determinar si la presencia de SRIS al ingreso en pacientes cirróticos hospitalizados está asociada a complicaciones o mortalidad. Materiales y métodos: Estudio de cohortes retrospectiva, realizado en el Hospital Nacional Daniel Alcides Carrión. Se admitieron pacientes cirróticos hospitalizados desde julio 2008 hasta diciembre 2010 sin comorbilidades importantes, neoplasia maligna, infección VIH, o estancia fue menor a 72 horas. Se evaluó presencia de SRIS al ingreso y la aparición de complicaciones o muerte después de 72 horas del ingreso. Resultados: Fueron 150 pacientes cirróticos admitidos, se excluyeron 6, tres por supervivencia menor a las 72 horas, uno por neoplasia, uno por insuficiencia cardiaca severa y dos por insuficiencia renal crónica. En total 144 pacientes ingresaron al estudio, 95 (66%) pacientes presentaron SRIS al ingreso. No hubo diferencia significativa en cuanto a edad, sexo, etiología, en ambos grupos. SRIS estuvo asociado a mayores puntajes de MELD y Child-Pugh Turcotte. De los pacientes con SRIS, 41 (43%) se complicaron y 16 (16,8%) fallecieron, mientras que del grupo sin SRIS 5 (10,2%) se complicaron y 2 (4%) fallecieron , ( p <0,0001y p =0,028 respectivamente). Las complicaciones más frecuentes fueron las infecciones y encefalopatía hepática. En el análisis multivariado SRIS estuvo asociado a complicaciones ( p <0,006) mas no a mortalidad ( p <0,276). Conclusiones: SRIS es frecuente en pacientes cirróticos hospitalizados y está asociado a complicaciones intrahospitalarias. / Objective: The systemic inflammation worsens circulatory disorders in cirrhotic patients and recently the systemic inflammatory response syndrome (SIRS) may be a prognostic indicator therein. The aim of the study was to determine whether the presence of SIRS at admission in hospitalized cirrhotic patients is associated with complications or mortality. Materials and methods: A retrospective cohorts study was conducted at the Daniel Alcides Carrion National Hospital. Hospitalized cirrhotic patients admitted from July 2008 to December 2010 without significant comorbidities, malignancy, HIV infection, or stay less than 72 hours were included. Presence of SIRS at admission and the occurrence of complications or death after 72 hours of admission were evaluated. Results: 150 cirrhotic patients were admitted, six were excluded; three for lower survival at 72 hours, one for neoplasia, one for severe heart failure and two for chronic renal failure. One hundred forty four patients were included, 95 (66%) patients had SIRS at admission. There was no significant difference in age, sex, etiology, in both groups. SIRS was associated with higher scores of MELD and Child-Turcotte Pugh. Of the group of patients with SIRS, 41 (43%) had complications and 16 (16.8%) died, while the group without SIRS 5 (10.2%) had complications and two (4%) died ( p <0.0001 and p =0.028 respectively). The most common complications were infections and hepatic encephalopathy. In multivariate analysis SIRS was associated with complications ( p <0.006) but not with mortality ( p <0.276). Conclusions: SIRS is common in hospitalized cirrhotic patients and is associated with in-hospital complications.

Objetivo: La inflamación sistémica empeora los trastornos circulatorios en el paciente cirrótico y recientemente el síndrome de respuesta inflamatoria sistémica (SRIS) podría ser un indicador pronóstico en ellos. El objetivo del estudio fue determinar si la presencia de SRIS al ingreso en pacientes cirróticos hospitalizados está asociada a complicaciones o mortalidad. Materiales y métodos: Estudio de cohortes retrospectiva, realizado en el Hospital Nacional Daniel Alcides Carrión. Se admitieron pacientes cirróticos hospitalizados desde julio 2008 hasta diciembre 2010 sin comorbilidades importantes, neoplasia maligna, infección VIH, o estancia fue menor a 72 horas. Se evaluó presencia de SRIS al ingreso y la aparición de complicaciones o muerte después de 72 horas del ingreso. Resultados: Fueron 150 pacientes cirróticos admitidos, se excluyeron 6, tres por supervivencia menor a las 72 horas, uno por neoplasia, uno por insuficiencia cardiaca severa y dos por insuficiencia renal crónica. En total 144 pacientes ingresaron al estudio, 95 (66%) pacientes presentaron SRIS al ingreso. No hubo diferencia significativa en cuanto a edad, sexo, etiología, en ambos grupos. SRIS estuvo asociado a mayores puntajes de MELD y Child-Pugh Turcotte. De los pacientes con SRIS, 41 (43%) se complicaron y 16 (16,8%) fallecieron, mientras que del grupo sin SRIS 5 (10,2%) se complicaron y 2 (4%) fallecieron, (p<0,0001y p=0,028 respectivamente). Las complicaciones más frecuentes fueron las infecciones y encefalopatía hepática. En el análisis multivariado SRIS estuvo asociado a complicaciones (p<0,006) mas no a mortalidad (p<0,276). Conclusiones: SRIS es frecuente en pacientes cirróticos hospitalizados y está asociado a complicaciones intrahospitalarias. / Objective: The systemic inflammation worsens circulatory disorders in cirrhotic patients and recently the systemic inflammatory response syndrome (SIRS) may be a prognostic indicator therein. The aim of the study was to determine whether the presence of SIRS at admission in hospitalized cirrhotic patients is associated with complications or mortality. Materials and methods: A retrospective cohorts study was conducted at the Daniel Alcides Carrion National Hospital. Hospitalized cirrhotic patients admitted from July 2008 to December 2010 without significant comorbidities, malignancy, HIV infection, or stay less than 72 hours were included. Presence of SIRS at admission and the occurrence of complications or death after 72 hours of admission were evaluated. Results: 150 cirrhotic patients were admitted, six were excluded; three for lower survival at 72 hours, one for neoplasia, one for severe heart failure and two for chronic renal failure. One hundred forty four patients were included, 95 (66%) patients had SIRS at admission. There was no significant difference in age, sex, etiology, in both groups. SIRS was associated with higher scores of MELD and Child-Turcotte Pugh. Of the group of patients with SIRS, 41 (43%) had complications and 16 (16.8%) died, while the group without SIRS 5 (10.2%) had complications and two (4%) died (p<0.0001 and p=0.028 respectively). The most common complications were infections and hepatic encephalopathy. In multivariate analysis SIRS was associated with complications (p<0.006) but not with mortality (p<0.276). Conclusions: SIRS is common in hospitalized cirrhotic patients and is associated with in-hospital complications. Key words: Liver cirrhosis; Systemic inflammatory response syndrome; Complications (source: MeSH NLM).

Student Number : 9903082V - MSc (Med) dissertation - Faculty of Health Sciences / Chronic infection with the hepatitis B virus (HBV) is endemic to sub-Saharan Africa and south-east Asia where it is a major risk factor for the development of cirrhosis and hepatocellular carcinoma (HCC). Currently available therapy is only effective in a small subset of chronic carriers. The development of novel treatment modalities for the management of HBV therefore remains an important global medical objective. Sequence plasticity of the HBV genome is limited by its small size and the overlapping nature of its open reading frames (ORFs). These features make HBV an ideal target for therapy based on nucleic acid hybridization. The use of ribozymes (RNA enzymes) and antisense molecules to inhibit gene expression is well documented. The recent discovery of RNA interference (RNAi) has added to the arsenal of therapy based on nucleic acid hybridization. RNAi is the process whereby short RNA duplexes (called short interfering RNA or siRNA) mediate the sequence-specific post-transcriptional silencing of genes homologous in sequence to the siRNA. siRNA function by guiding a protein complex (RNA Induced Silencing Complex or RISC) to target mRNA for degradation or translational repression. The protein X ORF (HBx ORF) is a conserved region of the HBV genome and is common to all viral transcripts. HBx is required for infection by the virus and plays an important role in the establishment of chronic infections in vivo as well as in the development of HCC. RNAi targeted against the HBx ORF may therefore prove useful as treatment of chronic HBV infection. Plasmid based expression cassettes capable of endogenously generating short hairpin RNA (shRNA) targeted to the HBx ORF were constructed. The shRNA function as substrates for the RNAi machinery and are processed into siRNA. The ability of the expression cassettes to knockdown markers of HBV gene expression was tested in a human hepatoma cell line. A panel of 10 U6 promoter-driven shRNA expression vectors was generated. The U6 promoter (an RNA polymerase III promoter) is normally involved in the transcription of small nuclear RNA and as such is ideal for the generation of shRNA of precisely defined length. Three cytomegalovirus (CMV) promoter-driven shRNA expression cassettes incorporating ribozymes that produce defined hairpin sequences were also generated. The CMV promoter (an RNA polymerase II) promoter is involved in the transcription of large messenger RNA. Two hammerhead ribozymes lying 5’ and 3’ of the shRNA encoding sequence were incorporated into the cassette. Cis-cleavage by the ribozymes releases a shRNA of defined length thereby overcoming the limitations imposed by extraneous sequences from CMV promoter-driven transcription. U6 promoter-driven shRNA expression vectors efficiently knocked down markers of HBV replication in liver cells. The CMV promoter-driven expression vectors were incapable of inhibiting HBV gene expression; however shRNA generated in vitro from these vectors mediated efficient knockdown of HBV replication. shRNA-mediated inhibition of gene expression therefore holds promise as a novel treatment strategy for the management of HBV and other mobile genetic elements.