京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第19599号 / 医博第4106号 / 新制||医||1014(附属図書館) / 32635 / 京都大学大学院医学研究科医学専攻 / (主査)教授 柳田 素子, 教授 妹尾 浩, 教授 浅野 雅秀 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

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Primary sclerosing cholangitis (PSC) is a rare inflammatory chronic liver disease that causes damage to the intra- and or extrahepatic bile ducts leading to cholestasis. As the disease proceeds the development of cirrhosis and eventually liver failure occurs. This study aims to determine the role of IgG subclasses in the prognosis of PSC and its outcome. A retrospective analysis was performed of 183 patients followed at the Department of Upper Abdominal Diseases at the Karolinska University Hospital. Factors that were analysed were sex, age at PSC diagnosis, total IgG values, IgG subclasses values and events of autoimmune hepatitis (AIH), inflammatory bowel disease (IBD), colectomy, cirrhosis, cholangitis, endoscopic retrograde cholangiopancreatography (ERCP), liver transplantation and cholangiocarcinoma. This study showed that high IgG4 levels were associated with a higher incidence of cirrhosis, liver transplantation, cholangitis and ERCP, while low IgG4 levels were associated with a prior IBD diagnosis. In conclusion, elevated IgG4 levels were associated with a higher occurrence of cirrhosis, cholangitis, ERCP and liver transplantation. It seems that IgG4 could be of importance for outcome prediction in PSC.

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Sulfur amino acids have critical function as intracellular redox buffers and maintain homeostasis in the external milieu by combating oxidative stress. Synthesis of glutathione (GSH) is regulated at a substrate level by cysteine, which is synthesized by homocysteine via the transsulfuration pathway. Oxidative stress and diminished glutathione pools play a sustained role in the pathogenesis of acute pancreatitis. One of the aims of this study was to experimentally address the temporal relationship between plasma sulfur amino acid levels in patients suffering from acute pancreatitis. The data indicated low concentration of cysteine initially, at levels similar to those of healthy controls. Glutathione was found reduced whilst cysteinyl-glycine and ¿- glutamyl transpeptidase activity were increased in both mild and severe attacks. As the disease progressed, glutathione and cysteinyl-glycine were further increased in mild attacks and cysteine levels correlated with homocysteine and ¿-glutamyl transpeptidase activity. The progress of severe attacks was associated with glutathione depletion, reduced ¿-glutamyl transpeptidase activity and increased cysteinyl-glycine, that correlated with glutathione depletion. The corollary that ample supply of cysteine and cysteinly-glycine does not contribute towards glutathione synthesis in acute pancreatitis poses an important issue that merits resolution. Heightened oxidative stress and depletion of glutathione rationalized the progression of disease in severe attacks. An upsurge that reactive oxygen species can shift redox state of cells is determined by the ratio of the abundant redox couples reduced and oxidized glutathione (GSH: GSSG) in cell. The study reported a novel methodology for quantification of total oxidized glutathione (tGSSG) and total glutathione (tGSH) in whole blood using reverse phase high performance liquid chromatography. The novelty of the method is ascertained by the use of a mercaptan scavenger 1, methyl-2-vinyl-pyridinium trifluromethanesulfonate for the total oxidized glutathione determination. The results reported permit quantitation of tGSSG and tGSH and was applied to a control group. Finally, the study was also focussed in developing a liquid chromatography-mass spectrometric method to evaluate free and conjugated bile acids in patients suffering from various degrees of cholestatic-hepatobiliary disorders. The study reported low levels of ursodeoxycholic acid (UDCA) and slightly high levels of lithocholic acid (LCA). All the primary bile acids seem to be conjugated with glycine and taurine amino acid.

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To evaluate the suitability of volume index measurement (VI) by either ultrasound (US) or computed tomography (CT) for the assessment of liver volume. Fifty-nine patients, 21 women, with a mean age of 66.8 ± 12.6 years underwent US of the liver followed immediately by abdominal CT. In US and CT imaging dorsoventral, mediolateral and craniocaudal liver diameters in their maximum extensions were assessed by two observers. VI was calculated by multiplication of the diameters divided by a constant (3.6). The liver volume determined by a manual segmentation in CT (“true liver volume”) served as gold standard. True liver volume and calculated VI determined by US and CT were compared using Bland–Altman analysis. Mean differences of VI between observers were − 34.7% (− 90.1%; 20.7%) for the US-based and 1.1% (− 16.1%; 18.2%) for the CT-based technique, respectively. Liver volumes determined by semi-automated segmentation, US-based VI and CT-based VI, were as follows: 1.500 ± 347cm3; 863 ± 371cm3; 1.509 ± 432cm3. Results showed a great discrepancy between US-based VI and true liver volume with a mean bias of 58.3 ± 66.9%, and high agreement between CT-based VI and true liver volume with a low mean difference of 4.4 ± 28.3%. Volume index based on CT diameters is a reliable, fast and simple approach for estimating liver volume and can therefore be recommended for clinical practice. The usage of US-based volume index for assessment of liver volume should not be used due to its low accuracy of US in measurement of liver diameters.

Motivation Alcohol consumption is one of the major risk factors of cardiovascular disease (CVD). Excessive alcohol drinking is the fifth leading cause of death worldwide and the prevalence of alcohol abuse continues to increase especially in low-income areas of sub-Saharan Africa. The alarming rate of urbanisation seems to be the driving force for excessive alcohol intake in the developing world. In addition to its influence on CVD, heavy drinking also results in a number of non-cardiovascular consequences that include injury, risky sexual behaviour, violent crime and family dysfunction among black South Africans, contributing to high mortality. Moreover, the highest number of individuals with human immunodeficiency virus (HIV) infection in South Africa is partly attributable to high intake of alcohol. HIV remains a major concern in South Africa with significant funding diverted to address the pandemic. The continued increases in mortality from preventable outcomes such as stroke, myocardial infarction and renal failure are largely due to urbanisation, poverty and dysfunctional health systems working with limited budgets. These are some of the factors requiring in-depth study of the scientific aspects of alcohol intake in South Africa. Although there is enough evidence that links excessive drinking with hypertension and CVD, the markers of alcohol intake – self reporting of alcohol, gamma-glutamyltransferase (GGT) and carbohydrate deficient transferrin – are still not specific enough to isolate other confounding factors in the association of alcohol intake with CVD. The markers of alcohol that independently predict CVD and mortality need to be explored. Finally, the severe lack of longitudinal investigations on alcohol-related hypertension development and total mortality in black South Africans has compromised the early identification of risk factors associated with these outcomes. This study will therefore attempt to address the limited availability of longitudinal studies and stimulate interest for continued investigation. Aim The aim of this study was to investigate whether alcohol intake of black South Africans is related to specific measures of cardiovascular function (change in blood pressure (BP), hypertension development) and mortality over a period of 5 years. Methodology This study was based on the international Prospective Urban and Rural Epidemiology (PURE) study which includes 26 countries, investigating the cause and development of cardiovascular risk factors in low, middle and high income countries. This South African leg of the PURE study started in 2005 in which the baseline data was collected from 2021 black South Africans from rural and urban areas in Ikageng, Ganyesa and Tlakgameng in the North West Province. Eleven participants presented with missing data, leaving 2010 participants with complete datasets at baseline. However, data from these 11 participants was useful, especially for Chapter 4. All participants gave informed consent and the Ethics committee of the North-West University (Potchefstroom Campus) approved the study. The follow-up data collection was done in 2010. General health questionnaires, anthropometric measurements, lipid profiles and cardiovascular measurements were taken both at baseline and follow-up using appropriate methods. We also collected blood samples and performed biochemical analyses for lipid markers, liver enzymes, inflammatory markers and percentage carbohydrate deficient transferrin (%CDT). Finally, we obtained data on cardiovascular and non-cardiovascular mortality through verbal autopsy and death certificates. We made use of analysis of variance (ANOVA) and Chi-square tests to compare means and proportions, respectively. We used dependent t-tests and the McNemar test to compare baseline and follow-up variables. Furthermore, we employed single and partial linear regression analyses to correlate alcohol markers with each other and with the cardiovascular measures. Multiple regression analyses were used to correlate dependent variables in the study with various independent variables as required. Finally, we employed multivariable-adjusted Cox regression analyses to assess the association of the selected alcohol markers with mortality while adjusting for several independent variables. Results and Conclusions of each manuscript - With the first research article (Chapter 4), we aimed to compare self-reported alcohol intake estimates with GGT and %CDT, considering their relationship with percentage change in brachial blood pressure (BP) and central systolic blood pressure (cSBP) over 5 years. The results indicated that only self-reported alcohol intake independently predicted % change in brachial BP and cSBP. This was not found for the biochemical markers GGT and %CDT. Self-reported alcohol intake seems to be an important measure to implement by health systems in low income areas of sub-Saharan Africa, where honest reporting is expected. - Given the likely presence of high GGT levels in both alcohol consumption and non-alcoholic fatty liver disease (NAFLD), the second manuscript (Chapter 5) aimed to compare the cardiovascular and metabolic characteristics of excessive alcohol users and individuals with suspected NAFLD (confirmed with self-report, GGT and %CDT). We found that different sex and cardiometabolic profiles characterised excessive alcohol users and individuals suspected with NAFLD. Lean body mass and male sex were the dominant characteristics in excessive alcohol use while the NAFLD group had a dysmetabolic profile with obese women making up the higher proportion of this group. In excessive alcohol users systolic blood pressure and pulse pressure were independently associated with high-density lipoprotein cholesterol. Diastolic blood pressure showed a significant correlation with waist circumference. These disparate profiles may guide healthcare practitioners in primary healthcare clinics to identify individuals with elevated GGT levels who may suffer from NAFLD or alcohol overuse. These results emphasise the importance of modifiable risk factors as the main contributors to CVD and that lifestyle change should be the main focus in developing countries such as South Africa. - The third manuscript (Chapter 6) aimed to determine the measure of alcohol intake (selfreported alcohol intake, GGT and %CDT) that related best with hypertension development, cardiovascular and all-cause mortality over 5 years in the same population of black South Africans. We found that GGT was the only independent predictor of hypertension development, cardiovascular as well as all-cause mortality. Moreover, self-reporting of alcohol intake predicted incident hypertension, confirming our findings from Chapter 4. The third marker, %CDT, a highly specific marker of alcohol intake, was not related with any outcome variable, perhaps due to its low sensitivity. Although self-reported alcohol intake is useful in low-resource primary healthcare settings, measurement of GGT is encouraged due to its predictive value for hypertension and mortality. GGT represents alcohol intake, non-alcoholic steatohepatitis and obesity - all known to have severe cardiovascular consequences. Discussion and Conclusions Excessive alcohol intake remains a major concern in the development of hypertension, CVD and premature death in sub-Saharan Africa. Despite their weaknesses such as bias and nonspecificity, self-reporting of alcohol consumption and GGT emerged as reliable alcohol markers that independently predicted 5-year change in BP, hypertension development and total mortality in this population. Serum %CDT did not show any association with the mentioned cardiovascular markers. Finally, we were also able to show that black South Africans with suspected NAFLD (i.e. with high GGT levels who do not consume alcohol) are typically obese women, whereas lean men were more likely to have high alcohol consumption. Further prospective investigations are encouraged regarding (a) these mentioned associations, as well as (b) other self-reporting estimates such as quantity and frequency of drinking and (c) the use of %CDT as a highly specific marker of alcohol intake. The simultaneous presence of HIV infection in alcohol abuse in this population also warrants further investigation. / PhD (Physiology), North-West University, Potchefstroom Campus, 2015