Biomedical subjects

Niamh Nolan

Publications and source records attributed to Niamh Nolan.

8 recordsLinked to original sources

PubMed2006

Assessment of fibrosis progression in untreated irish women with chronic hepatitis C contracted from immunoglobulin anti-D.

BACKGROUND & AIMS: In 1996 we initiated a retrospective-prospective study in 184 untreated women infected in 1977 with chronic hepatitis C virus (HCV). To provide insight into the natural history of HCV, we determined liver fibrosis outcomes and any predictors of such. METHODS: Baseline 1994 biopsy specimens (size, >or=15 mm; portal areas, >or=5) and sequential biopsy specimens were assessed by Ishak score for grade change (increase or decrease of >or=2 points) and stage progression or regression (increase or reduction of >or=1 point), the latter correlated with digital quantification of fibrosis percentage. RESULTS: No baseline biopsy specimens had cirrhosis, therefore all could potentially progress. Grade and stage scores decreased or increased significantly in 28% and 18% and 24% and 27% of patients, respectively. There was a positive correlation between baseline and sequential grade/stage scores (r = .39, P < .001), and between semiquantitative Ishak scores and fibrosis percentage (Spearman rho = .85; P < .01). Baseline alanine transaminase values (mean, 49 U/L; range, 23-363 U/L) correlated positively with changes in grade (r = .41, P < .01) and stage (r = .39, P < .01), and regression analyses indicated that baseline alanine transaminase value was a good predictor of such changes. Confounding variables (alcohol, smoking, and herbal and paracetamol [acetaminophen] use) did not correlate with histologic outcomes. CONCLUSIONS: In a follow-up study, 49% of patients showed no change in fibrosis, 24% showed regression, and only 27% showed progression, including 4 patients (2.1%) who developed stage 6 cirrhosis. Unidirectional sequential grade/stage concordance attested to biopsy sample reliability. Given the current age of these women in their fifth decade, some still may have a risk for more advanced liver disease, but for most of these patients it appears unlikely.

Adult↗

PubMed2004

Nitric oxide in early ischaemia reperfusion injury during human orthotopic liver transplantation.

BACKGROUND: Altered nitric oxide (NO) metabolism has been shown to contribute to ischemia-reperfusion (IR) injury in animal models. However, similar studies have not been performed in human liver transplantation (LT). In this study, we examined nitrate, nitrite, and nitrosothiols (NOx), NO synthases (endothelial [constitutive] nitric oxide synthase [eNOS] and inducible nitric oxide synthase [iNOS]), and nitrotyrosine in early IR injury after human LT. METHODS: Paired biopsies were obtained from nine donor livers before cold ischemia (retrieval biopsy) and after reimplantation (reperfusion biopsy). Sections were graded for reperfusion injury using the Suzuki score. NO was detected by chemiluminescence after reduction of NOx. Expression of eNOS and iNOS was by Western blot and reverse transcriptase polymerase chain reaction and peroxynitrite by immunodetection of 3-nitrotyrosine. RESULTS: Reperfusion biopsies showed histologic evidence of injury (median Suzuki score: retrieval 2, reperfusion 6, P=0.008) and neutrophil infiltration. NOx was reduced after reperfusion from 5.41 microM/100 mg (median, range 2.17-13.39 microM) to 3.51 microM (1.45-5.66 microM, P=0.05). eNOS protein was reduced after reperfusion from 0.6 units (median, range 0.45-1 unit) in retrieval biopsies to 0.39 units in reperfusion biopsies (range 0.2-0.79 units, P=0.007). There was no change in eNOS or iNOS mRNA expression or iNOS protein. Western blotting showed increased nitrotyrosine formation after reperfusion, median 0.42 (range 0.16-0.87) units in retrieval biopsies and 0.68 (0.29-1.06) units in reperfusion samples (P=0.007) and localized to periportal regions. CONCLUSIONS: iNOS protein may not contribute to early reperfusion injury during human LT. However, reduced NO bioavailability caused by reduced eNOS may contribute significantly to damage at this time point.

Adolescent↗

PubMed2004

Distinct MHC class I and II alleles are associated with hepatitis C viral clearance, originating from a single source.

The role of cytotoxic T lymphocyte responses, restricted by human leukocyte antigen (HLA) class I alleles, is recognized as highly significant in the successful clearance of hepatitis C virus (HCV). The frequency of class I alleles in females inoculated with HCV genotype 1b from a single source was examined for an association with outcome. Class I typing was performed using polymerase chain reaction sequence-specific primers in 227 female subjects: 141 had chronic infection and 86 had viral clearance. Statistical analysis included chi(2) testing and multiple logistic regression analysis. A*03, B*27, and Cw*01 occurred more frequently in those with viral clearance (39.5%, 14%, and 9.3%, respectively) compared with those with chronic infection (19.1%, 2.1%, and 1.4%, respectively; P < or = .005). B*08 occurred more often in those with chronic infection compared with viral clearance (39.7% vs. 19.8%; P =.002). In combination with previously reported class II allele associations, over 75% that successfully eliminate HCV carry either A*03, DRB1*0101, or *0401, compared with only 37% of those with chronic infection (P <.0001). The haplotypes A*03-B*07-DRB1*15-DQB1*0602 and A*02-B*27-Cw*01-DRB1*0101-DQB1*0501 are associated with viral clearance (P =.004 and.01, respectively). By multiple logistic regression analysis, the alleles A*03, B*27, DRB1*0101, *0401, and *15 are associated with viral clearance, and B*27 has the strongest association (odds ratio [OR] 7.99). The haplotype A*01-B*08-Cw*07-DRB1*03011-DQB1*0201 is associated with chronic infection (P =.002), being independent for DQB1*0201 (OR 0.27). In conclusion, certain class I alleles are associated with outcome in this homogeneous cohort. More significantly, either HLA-A*03, -DRB1*0101, or -*0401 are carried by an overwhelming majority of those subjects who successfully clear HCV.

Alleles↗

PubMed2003

Expansion of innate CD5pos B cells expressing high levels of CD81 in hepatitis C virus infected liver.

BACKGROUND/AIMS: Association of hepatitis C virus (HCV) with increased autoantibodies, mixed cryoglobulinaemia, non-Hodgkin's B-cell lymphoma and increased peripheral innate (CD5(pos)) B cells suggests a role for B-lymphocytes in the pathogenesis of HCV-infection. METHODS: Flow cytometry was used to estimate CD5(pos) B cell levels and CD81 co-expression in chronic HCV infection. Viral load was assessed using PCR. RESULTS: We demonstrate expansion of innate B cells in HCV-infected liver from patients with fibrosis score less than stage II (39%, % of total B cells, P=0.002) and end stage HCV cirrhosis (20%, P<0.05) compared with normal liver (8%). Expression of CD81, a signal transducing molecule and putative HCV receptor, was significantly increased on peripheral blood CD5(pos) B cells compared with conventional B cells (P=0.0001). Higher levels of CD81 on CD5(pos) B cells were more dramatic in the liver of HCV-infected individuals. However, no significant difference was observed in the viral load of CD5(pos)CD81(High) B cells and CD5(neg)CD81(Low) B cells. CONCLUSIONS: Increased expression of CD81 on innate B cells, a population that is expanded in the livers and peripheral blood of chronic HCV-infected patients, suggests a role in viral specific activation and clonal proliferation in chronic HCV infection.

Adult↗

PubMed2002

Comparative rates of nucleotide sequence variation in the hypervariable region of E1/E2 and the NS5b region of hepatitis C virus in patients with a spectrum of liver disease resulting from a common source of infection.

The association of the severity of liver disease and the molecular evolution of hepatitis C virus (HCV) during chronic infection remains unclear and controversial. To address this we have studied the interpatient variability in the nucleotide sequence of two regions of the HCV genome, E1/E2, which contain the hypervariable region 1 and the nonstructural NS5b region, in a cohort of Irish female patients who were all recipients of a single source of HCV genotype 1b-contaminated anti-D immunoglobulin in 1977 and 1978 and who over the subsequent 20 years developed a spectrum of liver disease. In addition, quasispecies analysis was used to evaluate intrapatient variability in the E1/E2 region in four patients with mild and four with severe disease. Phylogenetic and evolutionary rate analyses of the nucleotide sequences demonstrated that there was no significant difference between those who developed mild disease and those who had progressed to severe disease or cirrhosis. These findings suggest that other factors, either additional viral or host, may be important in the pathogenesis and clinical outcome of chronic hepatitis C virus infection.

Amino Acid Sequence↗

PubMed2002

Decrease in hepatic CD56(+) T cells and V alpha 24(+) natural killer T cells in chronic hepatitis C viral infection.

BACKGROUND/AIMS: The intrahepatic immune system is likely to play a key role in determining the outcome of hepatitis C virus (HCV) infection. The hepatic lymphocyte repertoire is characterised by high CD8/CD4 T cell ratios and large numbers of gamma delta T cells, natural killer (NK) cells, NK T cells and NK receptor-positive T cells. It is not known which of these populations contribute to immunity against HCV or immune pathology. METHODS: To explore the relative contributions of lymphocyte subpopulations, we have compared the intrahepatic lymphocyte repertoires and cytokine expression in 13 patients with mild chronic hepatitis C infection, 14 with end-stage hepatitis C cirrhosis and five histologically normal livers by flow cytometry and immunohistochemistry. RESULTS: CD4(+) T cells bearing alpha beta T cell receptors (TCR) were significantly expanded in livers with chronic HCV infection while CD56(+) alpha beta T cells and V alpha 24 TCR-positive T cells were significantly depleted. Expanded CD4(+)T cells were predominantly Th1 cells, producing interferon-gamma but not interleukin-4. CONCLUSIONS: Failure to resolve HCV infection may be due to deficient innate and/or memory immune responses, while Th1 cells may mediate immune pathology.

Adult↗

PubMed2002

Mast cell hyperplasia in chronic rejection after liver transplantation.

The pathogenesis of chronic hepatic allograft rejection is poorly understood. Recent studies suggested that hepatic mast cells may be involved in the pathogenesis of chronic cholestatic liver disease. Because chronic rejection after liver transplantation is predominantly a cholestatic process, the aim of this study is to determine whether hepatic mast cells are involved in its pathogenesis. Biopsy specimens from (1) normal livers (n = 5), (2) transplanted livers with end-stage chronic rejection (n = 8), and (3) transplanted livers with acute cellular rejection (mild, n = 7; moderate, n = 5; severe, n = 7) were studied. Biopsy specimens were stained immunohistochemically for mast cells with human antitryptase antibody. Mast cell density was significantly increased in the chronic-rejection group (4.9 +/- 0.6/mm2) compared with controls (2.9 +/- 0.5/mm2; P <.05). The percentage of portal tracts containing mast cells was significantly greater in chronic-rejection (89% +/- 8%) than control biopsy specimens (69% +/- 5%; P <.05), as was the average number of mast cells per portal tract (5.4 +/- 0.9 v 1.9 +/- 0.4 cells; P <.01). In chronic rejection, tissue mast cells frequently were seen surrounding damaged bile ducts in inflamed portal tracts. Neither mast cell density nor distribution was significantly different from controls in posttransplantation biopsy specimens with acute cellular rejection of mild, moderate, or severe degree. The finding of mast cells infiltrating portal tracts and surrounding damaged bile ducts in chronic rejection suggests that hepatic mast cells may be important effector cells in the pathogenesis of chronic rejection.

Adolescent↗

PubMedDate not supplied

Localization of T and B lymphocytes in histologically normal adult human donor liver.

BACKGROUND/AIMS: Donor liver suitable for successful transplantation often has one or more of a range of mild abnormalities including inflammation. Passenger leukocytes documented in donor liver are thought to result from inflammatory stimuli in response to ischemic, drug or alcohol related damage. The aim was to identify donor livers, which were free of any evidence of damage, and to determine if, and where, leukocytes were present in these pristine livers. METHODOLOGY: Eight of eighteen donor livers, examined by hematoxylin and eosin staining, were found to be free of any evidence of pathological damage. Sections from these livers were stained with antibodies against CD3 (T cell marker), CD20 (B cell marker) and CD45 (common leukocyte antigen). RESULTS: Each of these livers were found to have significant numbers of T lymphocytes, located mainly in the portal tracts but also scattered throughout the parenchyma. A similar distribution of B cells was detected but at much lower levels. CONCLUSIONS: The presence of lymphocytes in the human liver is usually considered a hallmark of pathology. The demonstration of significant lymphocyte populations in pristine liver, particularly in the parenchyma, supports the hypothesis that the human liver harbors tissue-resident lymphocytes.

Adolescent↗