PubMed Health⌕ Search

Biomedical subjects

Margaret Billingham

Publications and source records attributed to Margaret Billingham.

4 recordsLinked to original sources
PubMed2006

Gene expression profiles and B-type natriuretic peptide elevation in heart transplantation: more than a hemodynamic marker.

BACKGROUND: B-type natriuretic peptide (BNP) is chronically elevated in heart transplantation and reflects diastolic dysfunction, cardiac allograft vasculopathy, and poor late outcome. This investigation studied peripheral gene expression signatures of elevated BNP concentrations in clinically quiescent heart transplant recipients in an effort to elucidate molecular correlates beyond hemodynamic perturbations. METHODS AND RESULTS: We performed gene microarray analysis in peripheral blood mononuclear cells of 28 heart transplant recipients with clinical quiescence (absence of dyspnea or fatigue; normal left ventricular ejection fraction [EF >55%]; ISHLT biopsy score 0 or 1A; and normal hemodynamics [RAP <7 mm Hg, PCWP < or = 15 mm Hg, and CI > or = 2.5 L/min per m2]). BNP levels were performed using the Triage B-type Natriuretic Peptide test (Biosite Diagnostics Inc, San Diego, Calif) and median BNP concentration was 165 pg/mL. Seventy-eight probes (of 7370) mapped to 54 unique genes were significantly correlated with BNP concentrations (P<0.001). Of these, the strongest correlated genes (P<0.0001) were in the domains of gelsolin (actin cytoskeleton), matrix metallopeptidases (collagen degradation), platelet function, and immune activity (human leukocyte antigen system, heat shock protein, mast cell, and B-cell lineage). CONCLUSIONS: In the clinically quiescent heart transplant recipient, an elevated BNP concentration is associated with molecular patterns that point to ongoing active cardiac structural remodeling, vascular injury, inflammation, and alloimmune processes. Thus, these findings allude to the notion that BNP elevation is not merely a hemodynamic marker but should be considered reflective of integrated processes that determine the balance between active cardiac allograft injury and repair.

Aged↗
PubMed2005

Nodular endocardial infiltrates (Quilty lesions) cause significant variability in diagnosis of ISHLT Grade 2 and 3A rejection in cardiac allograft recipients.

BACKGROUND: Endomyocardial biopsy is used to guide therapy after heart transplantation. An accurate and reliable diagnosis of rejection is critical for proper patient management. METHODS: A sub-set of 827 biopsies from 273 patients were identified from 8 centers participating in the Cardiac Allograft Gene Expression Observational Study. These included all biopsies graded by local center pathologists as International Society for Heart and Lung Transplantation (ISHLT) Grade 1B or higher and also randomly chosen Grade 0 and 1A biopsies. Each of these cases was reviewed in a blinded manner by 3 study pathologists in the absence of clinical data. The study pathologists were assigned an ISHLT grade and noted nodular endocardial infiltrates (Quilty lesions). RESULTS: The study pathologists were significantly more likely than local pathologists to diagnose ISHLT Grade 0, 1A and 3B rejection and significantly less likely to diagnose ISHLT Grade 1B, 2 and 3A rejection. Concordance between local and study pathologists was lowest for Grade 2 (17% agreement). Quilty lesions were noted in 3.3% of local Grade 0 cases and in 31% and 37% of local Grade 2 and 3A cases, respectively. Quilty lesions were recognized by study pathologists in 35% of local Grade 2 cases "downgraded" to Grade 0 or 1, but in only 10% of local Grade 2 cases confirmed by study pathologists. CONCLUSIONS: The greatest variability between pathologists in application of the ISHLT grading system is in Grade 2 biopsies, and Quilty lesions are a major contributing factor to the lack of concordance. Accurate application of the ISHLT grading system requires improved recognition and understanding of Quilty lesions.

Adolescent↗
PubMed2004

Histological and immunological characteristics of, and the effect of immunosuppressive treatment on, xenograft vasculopathy.

Like allografts, vascularized xenografts are susceptible to a process of chronic rejection. We have used the hamster-to-rat aortic transplant model to study characteristics of this phenomenon and to determine whether it could be controlled or prevented by immunosuppressive therapy. Golden Syrian hamster aortas were transplanted into untreated Lewis rats, athymic rats, and Lewis rats receiving cyclosporin (10 mg/kg), leflunomide (5, 10 or 15 mg/kg), or 10 mg/kg of both drugs. Grafts were harvested on days 2, 7, 14, 28 and 56. Grafts and recipient spleens were analysed using computerized morphometry, immunohistochemistry and immunofluorescence. Blood was taken on various days for the measurement of anti-hamster antibodies (flow cytometry) and of the leflunomide metabolite A77 127. In untreated rats, by day 56, transplanted aortas developed a cell-free media with a mature neointimal lesion consisting of actin-positive cells, CD4 T cells, and macrophages. There were large increases in anti-hamster immunoglobulin M (IgM) and IgG, collections of proliferating cell nuclear antigen (PCNA)-positive cells in splenic germinal centres, and IgM, C3 and C5a deposition in aortas. In athymic recipients, the media architecture was preserved, and the changes in the neointima and in anti-hamster IgM and IgG were markedly abrogated, but not prevented. In Lewis rats receiving leflunomide, absence of circulating or deposited IgM did not prevent neointimal formation by day 14. Combination treatment was the most effective at preventing neointimal formation and humoral changes. Leflunomide monotherapy was the least effective. There were no changes in peak concentrations of the main metabolite of leflunomide over 8 weeks. The hamster-to-rat aortic transplant model is suitable for the study of xenograft vasculopathy, the histological and serological changes of which are predominantly T-cell dependent. Combination treatment with 10 mg/kg of cyclosporin and 10 mg/kg of leflunomide was most effective in preventing xenograft vasculopathy.

Animals↗