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Biomedical subjects

Geoffrey W McCaughan

Publications and source records attributed to Geoffrey W McCaughan.

At least 19 recordsLinked to original sources
PubMed2006

Dietary protein intakes in patients with hepatic encephalopathy and cirrhosis: current practice in NSW and ACT.

OBJECTIVE: To ascertain whether current practice in teaching hospitals in New South Wales and the Australian Capital Territory delivers adequate dietary protein in the management of malnutrition in adults with cirrhosis, in accordance with European Society for Clinical Nutrition and Metabolism (ESPEN) guidelines for nutrition in liver disease. STUDY DESIGN: Cross-sectional study of dietitians using a self-administered, mail-back survey. SETTING: Teaching hospitals in NSW and the ACT treating patients with cirrhosis. PARTICIPANTS: Dietitians seeing patients with cirrhosis in the 12 months prior to completing the survey. MAIN OUTCOME MEASURES: Current dietary protein prescription practice for patients with cirrhosis (with and without hepatic encephalopathy); use of nutritional supplements and enteral feeding for malnourished patients with cirrhosis. RESULTS: Dietitians following the ESPEN guidelines were in the minority: 36% of the dietitians recommended an adequate protein intake for patients with hepatic encephalopathy. Sixty-four per cent of the dietitians had received referrals from the medical team requesting inappropriate protein-restricted diets for patients without hepatic encephalopathy. Seventy-eight per cent of the dietitians requested clarification of the recommended nutritional management of patients with cirrhosis. CONCLUSION: Many medical and dietetic staff inappropriately restrict protein intake of patients with cirrhosis.

Adult↗
PubMed2006

The hepatic transcriptome in human liver disease.

The transcriptome is the mRNA transcript pool in a cell, organ or tissue with the liver transcriptome being amongst the most complex of any organ. Functional genomics methodologies are now being widely utilized to study transcriptomes including the hepatic transcriptome. This review outlines commonly used methods of transcriptome analysis, especially gene array analysis, focusing on publications utilizing these methods to understand human liver disease. Additionally, we have outlined the relationship between transcript and protein expressions as well as summarizing what is known about the variability of the transcriptome in non-diseased liver tissue. The approaches covered include gene array analysis, serial analysis of gene expression, subtractive hybridization and differential display. The discussion focuses on primate whole organ studies and in-vitro cell culture systems utilized. It is now clear that there are a vast number research opportunities for transcriptome analysis of human liver disease as we attempt to better understand both non-diseased and disease hepatic mRNA expression. We conclude that hepatic transcriptome analysis has already made significant contributions to the understanding of human liver pathobiology.

Journal Article↗
PubMed2006

Marked changes of the hepatic sinusoid in a transgenic mouse model of acute immune-mediated hepatitis.

BACKGROUND/AIMS: The liver sinusoidal endothelial cell (LSEC) is increasingly recognized as having an important role in hepatic immunity. However, the responses of LSECs and the hepatic sinusoid in immune-mediated hepatitis are poorly described. METHODS: We studied a transgenic mouse model of acute immune-mediated hepatitis: Met-Kb mice injected with T cells from Des-TCR mice. RESULTS: Hepatitis was characterized by lymphocyte infiltrates causing severe but transient liver damage. There were marked changes in the ultrastructure of the LSEC five days after injection of the T cells that coincided with the peak of the hepatitis. The porosity of fenestrations in the LSEC decreased and the endothelium became thickened. LSECs appeared to be markedly activated. These changes were associated with narrowing of the space of Disse, loss of hepatocellular microvilli and deposition of basal lamina. Lymphocytes were seen passing through fenestrations. Loss of fenestration in the LSEC prevented hepatitis induced by a second injection of lymphocytes on day 5. CONCLUSIONS: Structural changes in the LSEC occur during the peak of a mouse model of immune-mediated hepatitis. These changes were associated with attenuation of subsequent liver damage, suggesting that they may influence immunological responses mediated by LSECs or the passage of lymphocytes through LSEC fenestrations.

Acute Disease↗
PubMed2006

Intrahepatic gene expression in human alcoholic hepatitis.

BACKGROUND/AIMS: Alcoholic hepatitis remains an important cause of morbidity and mortality. Treatment remains unsatisfactory, in part, due to limited understanding of the pathogenesis. The aim of this study is to define the global intrahepatic expression profile of human alcoholic hepatitis. METHODS: Gene expression was analysed by DNA microarray on RNA isolated from liver of patients with alcoholic hepatitis (AH, n = 8), alcoholic steatosis (AS, n = 9) and explants from non-diseased donor liver controls (ND, n = 7). Differential expression of selected genes was confirmed by real-time RT-PCR and immunohistochemistry. RESULTS: Cluster analysis allowed differentiation of alcoholic hepatitis from alcoholic steatosis. The gene expression profile of AH revealed 586 genes differentially expressed from AS and 211 genes differentially expressed from that of ND liver. In comparison, only 98 genes were differentially expressed in AS from ND. Novel differentially expressed genes in AH in comparison to ND and AS included claudins, osteopontin, CD209, selenoprotein and genes related to bile duct proliferation. Real-time RT-PCR confirmed up-regulation of IL-8, osteopontin, and TNFRSF14 and down-regulation of SAMeS and CD209. CONCLUSIONS: This study has defined the intrahepatic gene expression profile of human alcoholic hepatitis and revealed a number of novel differentially expressed genes.

Adult↗
PubMed2006

Zoledronic acid prevents bone loss after liver transplantation: a randomized, double-blind, placebo-controlled trial.

BACKGROUND: Clinically important rapid bone loss occurs within 3 to 6 months after liver transplantation and may be associated with osteoporotic fractures. OBJECTIVE: To determine whether bisphosphonate treatment with zoledronic acid reduces transplant-related bone loss more than placebo in adults having liver transplantation for chronic liver disease. DESIGN: 12-month randomized, double-blind, placebo-controlled trial. SETTING: 2 large liver transplantation centers in Australia. PATIENTS: 62 adults having liver transplantation for chronic liver disease. INTERVENTIONS: Infusions of zoledronic acid, 4 mg (n = 32), or saline (n = 30) were given within 7 days of transplantation and again at months 1, 3, 6, and 9 after transplantation. All patients received supplementation with calcium carbonate, 600 mg/d, and ergocalciferol, 1000 U/d. MEASUREMENTS: The primary outcome was bone mineral density (BMD) measured by dual x-ray absorptiometry before transplantation and 3, 6, and 12 months later. Secondary outcomes included bone turnover markers that were measured before transplantation and 1, 3, 6, 9, and 12 months later. RESULTS: There were statistically significant interactions between treatment effects and time for BMD measurements at the lumbar spine (P = 0.002), femoral neck (P = 0.001), and total hip (P < 0.001). Differences in acute bone loss 3 months after transplantation favored zoledronic acid over placebo. Differences between groups in percentage change from baseline adjusted for baseline weight and serum parathyroid hormone (PTH) level were 4.0% (95% CI, 1.1% to 7.0%) for the lumbar spine, 4.7% (CI, 1.9% to 7.6%) for the femoral neck, and 3.8% (CI, 1.7% to 6.0%) for the total hip. At 12 months after transplantation, the difference in percentage change from baseline between the 2 groups adjusted for baseline weight and serum PTH level was 1.1% (CI, -2.1% to 4.4%) for the lumbar spine, 2.7% (CI, 0.0% to 5.4%) for the femoral neck, and 2.4% (CI, 0.1% to 4.7%) for the total hip. Treatment with zoledronic acid induced temporary secondary hyperparathyroidism and postinfusion hypocalcemia statistically significantly more often than did placebo. LIMITATIONS: The trial was not powered to assess fractures, and 10 of 62 (16%) patients were not included in adjusted analyses because of missing weight or serum PTH measurements. CONCLUSION: Treatment with zoledronic acid can prevent bone loss within the first year after liver transplantation.

Bone Density↗
PubMed2006

Predictors of relapse to harmful alcohol after orthotopic liver transplantation.

BACKGROUND: End-stage alcoholic liver disease (ALD) is a common indication for liver transplantation. Outcomes may be limited by return to harmful drinking. Previous studies have identified few predictors of drinking relapse. AIM: This study examined novel postulated predictors of relapse to drinking. METHOD: The case notes of all patients transplanted for ALD at the Royal Prince Alfred Hospital from 1987-2004 were reviewed. Pre-transplant characteristics were rated by a psychiatrist independent of the transplant team, blind to the outcome. Outcomes were rated by a second independent alcohol treatment specialist also blind to the pre-transplant ratings. RESULTS: Of 100 patients, 6 died before discharge from hospital, 4 had <6 months follow-up, 18 relapsed to harmful drinking, 10 drank below harmful levels, and 62 remained abstinent after a mean of 5.6 years follow-up. Univariate analyses identified six potential pre-transplant predictors of return to harmful drinking. These were a diagnosis of mental illness (of which all cases were of depression), the lack of a stable partner, grams per day consumed in the years before assessment for transplant, reliance on 'family or friends' for post-transplant support, tobacco consumption at time of assessment, and lack of insight into the alcohol aetiology. Duration of pre-transplant abstinence and social class by occupation did not predict relapse. A multivariate model based on the above characteristics correctly predicted 89% of the outcomes. CONCLUSION: A model based on readily defined behaviours and psychosocial factors predicted relapse to harmful drinking after transplant for ALD. This model may improve assessment and post-transplant management of patients with advanced ALD.

Alcoholism↗
PubMed2006

T lymphocytes interact with hepatocytes through fenestrations in murine liver sinusoidal endothelial cells.

The liver has an established ability to induce tolerance. Recent evidence indicates that this unique property might be related to its distinctive architecture allowing T cells to be activated in situ independently of lymphoid tissues. Unlike lymph node-activated T cells, liver-activated T cells are short-lived, a mechanism that might contribute to the "liver tolerance effect." Although the potential role of hepatocytes as tolerogenic antigen-presenting cells has been demonstrated, the question as to whether these cells are able to interact with CD8(+) T cells in physiological settings remains controversial. Contradicting the immunological dogma stating that naïve T lymphocytes are prevented from interacting with parenchymal cells within non-lymphoid organs by an impenetrable endothelial barrier, we show here that the unique morphology of the liver sinusoidal endothelial cell (LSEC) permits interactions between lymphocytes and hepatocytes. Using electron microscopy, we demonstrate that liver resident lymphocytes as well as circulating naïve CD8(+) T cells make direct contact with hepatocytes through cytoplasmic extensions penetrating the endothelial fenestrations that perforate the LSECs. Furthermore, the expression of molecules required for primary T cell activation, MHC class I and ICAM-1, is polarized on hepatocytes to the perisinusoidal cell membrane, thus maximizing the opportunity for interactions with circulating lymphocytes. In conclusion, this study has identified, at the ultrastructural level, a unique type of interaction between naïve T lymphocytes and liver parenchymal cells in vivo. These results hold implications for the pathogenesis of viral hepatitis in which hepatocytes may represent the main antigen-presenting cell, and for the development of immune tolerance as lymphocytes pass through the liver.

Animals↗
PubMed2006

Hereditary lysozyme amyloidosis: spontaneous hepatic rupture (15 years apart) in mother and daughter. role of emergency liver transplantation.

Hepatic rupture is a rare condition, and treatment options are very limited. We report a case of hepatic rupture secondary to hereditary lysozyme amyloidosis that was successfully treated by liver transplantation. The mother of this patient had presented in an identical fashion 15 years earlier in the pretransplant era and died very rapidly.

Adult↗
PubMed2006

Vitamin D replacement for cirrhosis-related bone disease.

The osteoporotic fracture rate in patients with chronic liver disease is approximately twice that of age-matched, control individuals. About 66% of patients with moderately severe cirrhosis and 96% of patients awaiting liver transplantation have vitamin D deficiency. Studies have shown a strong correlation between vitamin D deficiency and bone density, particularly in the hip. Previous studies of vitamin D therapy in cirrhosis-related bone disease have had major design flaws. Most reports and guidelines on the treatment of hepatic bone disease have concluded that vitamin D deficiency does not have a significant pathogenetic role in the development of osteoporosis in cirrhosis, and that there is no evidence for a therapeutic effect of vitamin D supplementation. Conversely, it is generally recommended that patients with cirrhosis and low bone density should receive calcium and vitamin D supplementation; yet there is a paucity of reliable data on the optimal doses to use, as well as a lack of clearly demonstrated benefit. We believe that clinical trials of vitamin D therapy in these patients with liver disease are warranted. As low-dose oral supplementation often will not normalize vitamin D levels or suppress parathyroid hormone activity in cirrhotic patients, high-dose, parenteral vitamin D might be preferable, but further long-term studies are required to assess the benefits and safety of this approach.

Diphosphonates↗
PubMed2006

Extraenzymatic functions of the dipeptidyl peptidase IV-related proteins DP8 and DP9 in cell adhesion, migration and apoptosis.

The dipeptidyl peptidase IV gene family contains the four peptidases dipeptidyl peptidase IV, fibroblast activation protein, dipeptidyl peptidase 8 and dipeptidyl peptidase 9. Dipeptidyl peptidase IV and fibroblast activation protein are involved in cell-extracellular matrix interactions and tissue remodeling. Fibroblast activation protein is upregulated and dipeptidyl peptidase IV is dysregulated in chronic liver disease. The effects of dipeptidyl peptidase 8 and dipeptidyl peptidase 9 on cell adhesion, cell migration, wound healing and apoptosis were measured by using green fluorescent protein fusion proteins to identify transfected cells. Dipeptidyl peptidase 9-overexpressing cells exhibited impaired cell adhesion, migration in transwells and monolayer wound healing on collagen I, fibronectin and Matrigel. Dipeptidyl peptidase 8-overexpressing cells exhibited impaired cell migration on collagen I and impaired wound healing on collagen I and fibronectin in comparison to the green fluorescent protein-transfected controls. Dipeptidyl peptidase 8 and dipeptidyl peptidase 9 enhanced induced apoptosis, and dipeptidyl peptidase 9 overexpression increased spontaneous apoptosis. Mechanistic investigations showed that neither the catalytic serine of dipeptidyl peptidase 8 or dipeptidyl peptidase 9 nor the Arg-Gly-Asp integrin-binding motif in dipeptidyl peptidase 9 were required for the impairment of cell survival, cell adhesion or wound healing. We have previously shown that the in vitro roles of dipeptidyl peptidase IV and fibroblast activation protein in cell-extracellular matrix interactions and apoptosis are similarly independent of catalytic activity. Dipeptidyl peptidase 9 overexpression reduced beta-catenin, tissue inhibitor of matrix metalloproteinases 2 and discoidin domain receptor 1 expression. This is the first demonstration that dipeptidyl peptidase 8 and dipeptidyl peptidase 9 influence cell-extracellular matrix interactions, and thus may regulate tissue remodeling.

Adenosine Deaminase↗
PubMed2005

Molecular characterization of a novel dipeptidyl peptidase like 2-short form (DPL2-s) that is highly expressed in the brain and lacks dipeptidyl peptidase activity.

DPL2 (DPP10) found at chromosome 2q14.1 is a member of the dipeptidyl peptidase IV (DPIV) gene family. Here we characterize a novel short DPL2 isoform (DPL2-s), a 789-amino acid protein, that differs from the previously described long DPL2 isoform (DPL2-l) at the N-terminal cytoplasmic domain by 13 amino acids. The two DPL2 isoforms use alternate first exons. DPL2 mRNA was expressed mainly in the brain and pancreas. Multiple forms of recombinant DPL2-s protein were observed in 293T cells, having mobilities 96 kDa, 100 kDa, and approximately 250 kDa which may represent soluble DPL2, transmembrane DPL2 and multimeric DPL2 respectively. DPL2 is glycosylated as a band shift is observed following PNGase F deglycosylation. DPL2-s was expressed primarily on the cell surface of transfected 293T and PC12 cells. DPL2-s exhibits high sequence homology with other DPIV peptidases, but lacks a catalytic serine residue and lacks dipeptidyl peptidase activity. Substitutions of Gly(644)-->Ser, Lys(643)Gly(644)-->TrpSer, or Asp(561)Lys(643)Gly(644)-->TyrTrpSer in the catalytic motif did not confer dipeptidyl peptidase activity upon DPL2-s. Thus, although DPL2 is similar in structure and sequence to the other dipeptidyl peptidases, it lacks vital residues required to confer dipeptidyl peptidase activity and has instead evolved features that enable it to act as an important component of voltage-gated potassium channels.

Alternative Splicing↗
PubMed2005

Immune-mediated hepatitis drives low-level fusion between hepatocytes and adult bone marrow cells.

BACKGROUND/AIMS: The role of adult bone marrow-derived cells (BMC) in hepatic regeneration is controversial. Both transdifferentiation of BMC as well as fusion with hepatocytes have been suggested in toxin-based and genetic selection models. METHODS: We have developed a transgenic mouse model of immune-mediated hepatitis to clarify the role of BMC in liver regeneration following injury mediated by T cells. RESULTS: Repeated adoptive transfer of transgenic T cells into bone marrow chimeras resulted in multiple waves of hepatitis. Hepatocytes derived from donor bone marrow were identified using a self-protein that does not interfere with hepatocyte function and proliferation in recipient animals. Some cells contained one recipient nucleus and another independent donor bone marrow-derived nucleus, suggesting that cellular fusion plays some role in liver repair after immune hepatitis. However, despite pronounced infiltration by myeloid cells, the frequency of fusion was extremely low. CONCLUSIONS: This study provides a unique, clinically relevant model in which fusion hepatocytes can be purified and characterized by the expression of donor MHC antigen. It demonstrates that although fusion between BMC and hepatocytes occurs under conditions of inflammation that correspond to human disease, its frequency needs to be increased to be of any therapeutic value.

Animals↗
PubMed2005

Hepascore: an accurate validated predictor of liver fibrosis in chronic hepatitis C infection.

BACKGROUND: Staging hepatic fibrosis by liver biopsy guides prognosis and treatment of hepatitis C, but is invasive and expensive. We sought to create an algorithm of serum markers that accurately and reliably predict liver fibrosis stage among hepatitis C patients. METHODS: Ten biochemical markers were measured at time of liver biopsy in 117 untreated hepatitis C patients (training set). Multivariate logistic regression and ROC curve analyses were used to create a predictive model for significant fibrosis (METAVIR F2, F3, and F4), advanced fibrosis (F3 and F4), and cirrhosis (F4). The model was validated in 104 patients from other institutions. RESULTS: A model (Hepascore) of bilirubin, gamma-glutamyltransferase, hyaluronic acid, alpha(2)-macroglobulin, age, and sex produced areas under the ROC curves (AUCs) of 0.85, 0.96, and 0.94 for significant fibrosis, advanced fibrosis, and cirrhosis, respectively. In the training set, a score > or = 0.5 (range, 0.0-1.0) was 92% specific and 67% sensitive for significant fibrosis, a score <0.5 was 81% specific and 95% sensitive for advanced fibrosis, and a score <0.84 was 84% specific and 71% sensitive for cirrhosis. Among the validation set, the AUC for significant fibrosis, advanced fibrosis, and cirrhosis were 0.82, 0.90, and 0.89, respectively. A score > or = 0.5 provided a specificity and sensitivity of 89% and 63% for significant fibrosis, whereas scores <0.5 had 74% specificity and 88% sensitivity for advanced fibrosis. CONCLUSIONS: A model of 4 serum markers plus age and sex provides clinically useful information regarding different fibrosis stages among hepatitis C patients.

Adult↗
PubMed2005

Posttransplant interleukin-4 treatment converts rat liver allograft tolerance to rejection.

BACKGROUND: Previous studies showed that liver transplant rejection in the Piebald Virol Glaxo (PVG)-to-Lewis combination was associated with more intragraft interleukin (IL)-4 mRNA expression than in spontaneously tolerant grafts in the PVG-to-Dark Agouti (DA) combination. There was also immunoglobulin (Ig) G1 antibody deposition, suggesting an IL-4-induced IgG class switch in rejection. The aim of this study was to investigate whether IL-4 treatment converts PVG-->DA liver transplant tolerance to rejection. METHODS: DA (RT1a) rats were recipients of orthotopic PVG (RT1c) liver transplants and DA liver transplants were syngeneic controls. Supernatant from IL-4-transfected Chinese hamster ovary cells (0.5 mL, 30,000 U) or from untransfected cells was injected intraperitoneally on days 3 through 7. Samples were taken for immunohistochemical staining of frozen tissue sections to analyze cellular infiltrate and antibody deposition. RESULTS: IL-4 treatment significantly reduced survival of liver allografts from greater than 100 days in untreated animals to 9 days (P=0.004). Pathologic analysis of IL-4-treated animals showed that death was caused by liver transplant rejection, with a heavy infiltrate of mononuclear cells, disruption of portal tract areas, and infarction. Immunohistochemistry revealed an extensive infiltrate of T cells, CD25-expressing cells, and B cells that was similar to the level in PVG--> Lewis liver allograft recipients that reject the liver. There was also a more extensive monocyte-macrophage infiltrate and more major histocompatibility complex class II expression in IL-4-treated animals compared with untreated animals. There was moderate increase of IgM, little IgG1, and no IgE or IgG2a antibody deposition. CONCLUSIONS: IL-4, a T-helper type 2 cytokine that has previously been shown to inhibit delayed-type hypersensitivity responses such as rejection, was found to promote rejection of liver allografts. There was only slight evidence of a graft-specific antibody response, showing that IL-4 induces liver allograft rejection in association with some, but not all, of the changes accompanying rejection in the PVG-->Lewis strain combination.

Animals↗
PubMed2005

Fibroblast activation protein increases apoptosis, cell adhesion, and migration by the LX-2 human stellate cell line.

Injury and repair in chronic liver disease involve cell adhesion, migration, apoptosis, proliferation, and a wound healing response. In liver, fibroblast activation protein (FAP) has both collagenase and dipeptidyl peptidase IV (DPIV) activities and is expressed only by activated hepatic stellate cells (HSC) and myofibroblasts, which produce and degrade extracellular matrix (ECM). FAP was colocalized with collagen fibers, fibronectin, and collagen type I in human liver. FAP function was examined in vitro by expressing green fluorescent protein FAP fusion protein in cell lines cultured on collagen-I, fibronectin, and Matrigel. Glutamates at 203 and 204 as well as serine624 of FAP were essential for peptidase activity. Human embryonic kidney 293T cells overexpressing FAP showed reduced adhesion and migration. FAP overexpression in the human HSC line LX-2 caused increased cell adhesion and migration on ECM proteins as well as invasion across transwells in the absence or presence of transforming growth factor beta-1. FAP overexpression enhanced staurosporine streptomyces-stimulated apoptosis in both cell lines. Interestingly, the enzyme activity of FAP was not required for these functions. Overexpressing FAP increased the expression of matrix metalloproteinase-2 and CD44 and reduced integrin-beta1 expression in 293T cells, suggesting potential pathways of FAP-mediated impairment of cell adhesion and migration in this epithelial cell line. In conclusion, these findings further support a pro-fibrogenic role for FAP by indicating that, in addition to its enzymatic functions, FAP has important nonenzymatic functions that in chronic liver injury may facilitate tissue remodeling through FAP-mediated enhancement of HSC cell adhesion, migration, and apoptosis.

Antigens, Neoplasm↗