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Biomedical subjects

A M Flanagan

Publications and source records attributed to A M Flanagan.

At least 19 recordsLinked to original sources
PubMed2006

Neurofibromatosis presenting with a cherubism phenotype.

We report on a child who presented clinical manifestations of both neurofibromatosis type 1 (NF1) and cherubism. With genetic testing, we found a mutation in the NF-1 gene, confirming the neurocutaneous disorder. Histology when correlated with radiological evaluation of a mandibular biopsy was consistent with cherubism. This is the first report in the literature of a child with proven neurofibromatosis type 1 and cherubism without extragnathic lesions. This emphasises that cherubism is a clinical phenotype that can be associated with a number of germline mutations involving SH3BP2, PTPN11 and NF1.

Adolescent↗
PubMed2006

Brachyury, a crucial regulator of notochordal development, is a novel biomarker for chordomas.

Chordomas are malignant tumours that occur along the spine and are thought to derive from notochordal remnants. There is significant morphological variability between and within chordomas, with some showing prominent areas of chondroid differentiation. Our microarray data from a broad range of connective tissue neoplasms indicate that, at the transcriptional level, chordomas resemble cartilaginous neoplasms. Here we show that chordomas express many genes known to be involved in cartilage development, but they also uniquely express genes distinguishing them from chondroid neoplasms. The brachyury transcription factor, known to be involved in notochordal development, is only expressed by chordomas. Using a polyclonal antibody, we show that brachyury is expressed in the embryonic notochord and in all 53 chordomas analysed, labelling both chondroid and chordoid areas of these tumours. In contrast, the protein was not detected in over 300 neoplasms, including 163 chondroid tumours. Brachyury was not detected in the nucleus pulposus, arguing against the hypothesis that this tissue derives directly from the notochord. These data provide compelling evidence that chordomas derive from notochord and demonstrate that brachyury is a specific marker for the notochord and notochord-derived tumours.

Biomarkers, Tumor↗
PubMed2006

Who is the ideal candidate for autologous chondrocyte implantation?

We investigated the prognostic indicators for collagen-covered autologous chondrocyte implantation (ACI-C) performed for symptomatic osteochondral defects of the knee. We analysed prospectively 199 patients for up to four years after surgery using the modified Cincinnati score. Arthroscopic assessment and biopsy of the neocartilage was also performed whenever possible. The favourable factors for ACI-C include younger patients with higher pre-operative modified Cincinnati scores, a less than two-year history of symptoms, a single defect, a defect on the trochlea or lateral femoral condyle and patients with fewer than two previous procedures on the index knee. Revision ACI-C in patients with previous ACI and mosaicplasties which had failed produced significantly inferior clinical results. Gender (p = 0.20) and the size of the defect (p = 0.97) did not significantly influence the outcome.

Adolescent↗
PubMed2006

Collagen-covered autologous chondrocyte implantation for osteochondritis dissecans of the knee: two- to seven-year results.

We prospectively studied the clinical, arthroscopic and histological results of collagen-covered autologous chondrocyte implantation (ACI-C) in patients with symptomatic osteochondritis dissecans of the knee. The study included 37 patients who were evaluated at a mean follow-up of 4.08 years. Clinical results showed a mean improvement in the modified Cincinnati score from 46.1 to 68.4. Excellent and good clinical results were seen in 82.1% of those with juvenile-onset osteochondritis dissecans but in only 44.4% of those with adult-onset disease. Arthroscopy at one year revealed International Cartilage Repair Society grades of 1 or 2 in 21 of 24 patients (87.5%). Of 23 biopsies, 11 (47.8%) showed either a hyaline-like or a mixture of hyaline-like and fibrocartilage, 12 (52.2%) showed fibrocartilage. The age at the time of ACI-C determined the clinical outcome for juvenile-onset disease (p = 0.05), whereas the size of the defect was the major determinant of outcome in adult-onset disease (p = 0.01).

Adolescent↗
PubMed2005

Synovial sarcoma with radiological appearances of primitive neuroectodermal tumour/Ewing sarcoma: differentiation by molecular genetic studies.

Synovial sarcoma (SS) arises in soft tissues but may invade adjacent bone. We describe a case of SS presenting as aggressive lysis of the proximal ulna, the imaging of which suggested a primary bone lesion. Needle biopsy showed a "small round blue cell tumour", and a primitive neuroectodermal tumour (PNET)/Ewing sarcoma was suggested on the basis of the imaging appearances. The definitive diagnosis of synovial sarcoma was made following molecular genetic studies, which demonstrated a fusion product incorporating the genes SYT and SSX1. The importance of correct diagnosis to guide appropriate management, and, therefore, the necessity for molecular genetic studies, is discussed.

Adult↗
PubMed2005

High peripheral blood progenitor cell counts enable autologous backup before stem cell transplantation for malignant infantile osteopetrosis.

Autosomal recessive osteopetrosis (OP) is a rare, lethal disorder in which osteoclasts are absent or nonfunctional, resulting in a bone marrow cavity insufficient to support hematopoiesis. Because osteoclasts are derived from hematopoietic precursors, allogeneic hematopoietic cell transplantation can cure the bony manifestations of the disorder. However, high rates of graft failure have been observed in this population. It is not possible to harvest bone marrow from these patients for reinfusion should graft failure be observed. We report that 8 of 10 patients with OP had high numbers of circulating CD34(+) cells (3% +/- 0.9%). This increased proportion of peripheral CD34(+) cells made it possible to harvest 2 x 10(6) CD34(+) cells per kilogram with a total volume of blood ranging from 8.3 to 83.7 mL (1.3-11.6 mL/kg). In addition, colony-forming assays documented significantly more colony-forming unit-granulocyte-macrophage and burst-forming unit-erythroid in the blood of osteopetrotic patients compared with controls; the numbers of colony-forming units approximated those found in control marrow. We conclude that OP patients with high levels of circulating CD34(+) are candidates for peripheral blood autologous harvest by limited exchange transfusion. These cells are then available for reinfusion should graft failure be observed in patients for whom retransplantation is impractical.

Antigens, CD34↗
PubMed2005

Autologous chondrocyte implantation versus matrix-induced autologous chondrocyte implantation for osteochondral defects of the knee: a prospective, randomised study.

Autologous chondrocyte implantation (ACI) is used widely as a treatment for symptomatic chondral and osteochondral defects of the knee. Variations of the original periosteum-cover technique include the use of porcine-derived type I/type III collagen as a cover (ACI-C) and matrix-induced autologous chondrocyte implantation (MACI) using a collagen bilayer seeded with chondrocytes. We have performed a prospective, randomised comparison of ACI-C and MACI for the treatment of symptomatic chondral defects of the knee in 91 patients, of whom 44 received ACI-C and 47 MACI grafts. Both treatments resulted in improvement of the clinical score after one year. The mean modified Cincinnati knee score increased by 17.6 in the ACI-C group and 19.6 in the MACI group (p = 0.32). Arthroscopic assessments performed after one year showed a good to excellent International Cartilage Repair Society score in 79.2% of ACI-C and 66.6% of MACI grafts. Hyaline-like cartilage or hyaline-like cartilage with fibrocartilage was found in the biopsies of 43.9% of the ACI-C and 36.4% of the MACI grafts after one year. The rate of hypertrophy of the graft was 9% (4 of 44) in the ACI-C group and 6% (3 of 47) in the MACI group. The frequency of re-operation was 9% in each group. We conclude that the clinical, arthroscopic and histological outcomes are comparable for both ACI-C and MACI. While MACI is technically attractive, further long-term studies are required before the technique is widely adopted.

Adolescent↗
PubMed2004

Chondroid lipoma: correlation of imaging findings and histopathology of an unusual benign lesion.

The imaging findings of soft tissue tumours are often non-specific and generally require biopsy to differentiate between benign and malignant lesions. The finding of curvilinear, annular or amorphous mineralisation in an enlarging mass has sinister connotations. In this case report, we present the imaging findings with histological correlation of a chondroid lipoma, an unusual benign soft tissue tumour, which presented with radiographic evidence of calcification, an imaging finding not previously described. We also describe the ultrasound appearance and certain MR imaging appearances that have not been previously attributed to this tumour in the few reported cases.

Adult↗
PubMed2002

Low frequency of somatic mutations in the FH/multiple cutaneous leiomyomatosis gene in sporadic leiomyosarcomas and uterine leiomyomas.

Germline mutations in the fumarate hydratase gene at 1q43 predispose to dominantly inherited skin and uterine leiomyomata and leiomyosarcomas. The enzyme, which is a component of the tricarboxylic acid cycle, acts as a tumour suppressor. To evaluate fumarate hydratase in respective sporadic tumours, we analysed a series of 26 leiomyosarcomas and 129 uterine leiomyomas (from 21 patients) for somatic mutations in fumarate hydratase and allelic imbalance around 1q43. None of the 26 leiomyosarcomas harboured somatic mutations in fumarate hydratase. Fifty per cent of leiomysarcomas tested showed evidence of allelic imbalance at 1q, but this was not confined to the vicinity of fumarate hydratase. Only 5% (seven out of 129) of the leiomyomas showed allele imbalance at 1q42-q43 and no somatic mutations in fumarate hydratase were observed. Our findings indicate that mutations in fumarate hydratase do not play a major role in the development of sporadic leiomyosarcomas or uterine leiomyomas

Adult↗
PubMed2002

A feline assay using osteoclasts generated in vitro from peripheral blood for screening anti-resorptive agents.

Musculo-skeletal diseases are a major cause of pain and suffering in cats and several conditions involve increased bone resorption by osteoclasts. However, little is known about the biology of these cells in the cat. In this study we established a method to generate feline osteoclasts from blood mononuclear cells stimulated by macrophage colony stimulating factor (M-CSF) and receptor activator of NF-kappaB ligand (RANKL). Cultured osteoclasts are multinucleated, express tartrate resistant acid phosphatase (TRAP), form F-actin rings and resorb bone. They express alpha(v)beta3 vitronectin receptor and osteoclast enzymes, cathepsin K and MMP9; the myeloid antigen, CD18, and the megakaryocyte/platelet integrin, CD41, are absent. This phenotype is typical of osteoclasts from other species. Three resorption inhibitors were examined for activity against feline osteoclasts. Calcitonin, bisphosphonate and RGD integrin inhibitory peptide all reduced bone resorption at doses similar to those efficacious in rabbit or human. We conclude that blood-derived osteoclast cultures are a suitable in vitro system for assessing the ability of drugs to inhibit bone resorption in domestic cats.

Acid Phosphatase↗
PubMed2002

Macrophage colony-stimulating factor and receptor activator NF-kappaB ligand fail to rescue osteoclast-poor human malignant infantile osteopetrosis in vitro.

Malignant infantile osteopetrosis (MIOP) is a disease characterized by failure in bone resorption, leading to dense fragile bones with a severely reduced bone marrow cavity. Normal or increased numbers of osteoclasts are present in the common variant of this disease; in such cases, the defect is likely to be inherent to the mature osteoclast and can be cured by bone marrow transplantation. However, MIOP also results from failure of osteoclast formation (osteoclast-poor MIOP). We report on two infants diagnosed with osteoclast-poor MIOP and utilize modern cell culture techniques to investigate the pathogenesis of disease. Peripheral blood mononuclear cells (PBMNCs) from these children were cultured in the presence of recombinant macrophage colony-stimulating factor and receptor activator NF-kappaB ligand for up to 3 weeks. Control cultures included PBMNCs from age-matched children, one of whom had an osteoclast-rich form of MIOP. Formation of osteoclasts (cells coexpressing vitronectin receptor and F-actin rings) occurred in all the control cultures. Significant bone resorption occurred in cultures from PBMNCs of the healthy individuals, whereas almost no bone resorption occurred in the osteoclast-rich MIOP cultures. In contrast, PBMNC cultures from the osteoclast-poor MIOP child formed only very occasional small F-actin ring-positive osteoclasts, which coexpressed vitronectin receptor and cathepsin K, and extremely rare foci of resorption. Because neither macrophage colony-stimulating factor nor receptor activator NF-kappaB ligand rescued the defect in osteoclast differentiation in the two cases of osteoclast-poor MIOP in vitro, there would be little benefit in treating these children with either of these recombinant proteins. Finally, these results demonstrate that this experimental culture model replicates the human osteopetrosis phenotype observed in vivo and should prove useful in analyzing the pathogenesis of the various forms of MIOP.

Actins↗
PubMed2002

Novel therapeutic targets in osteoporosis.

Osteoporosis is a common condition in which significant bone loss occurs resulting in an increased risk of sustaining fractures. Several licensed therapies are available to treat this condition, which suffer from several disadvantages including limited efficacy, high cost and poor long-term patient adherence as a consequence of significant side effects and inconvenient methods of administration. A wide range of therapeutic targets have been developed to provide a basis for developing newer therapies which overcome these limitations. These can be subdivided into those that are primarily directed towards inhibiting osteoclast-dependent bone resorption and those that stimulate osteoblastic bone formation. Targets can be grouped as follows: systemic factors such as steroid and peptide hormones; local factors produced in bone involved in osteoblast and osteoclastic regulation; and cellular targets such as cell membrane receptors and attachment proteins, cellular enzymes and nuclear transcription factors. To date, only a small proportion of these targets have yielded novel compounds to have entered clinical trials. However, it is anticipated that these will provide the basis for significant numbers of new therapies for osteoporosis in the foreseeable future.

Animals↗
PubMed2001

Transforming growth factor-beta1 (TGF-beta) stimulates the osteoclast-forming potential of peripheral blood hematopoietic precursors in a lymphocyte-rich microenvironment.

Osteoclasts are generated from peripheral blood mononuclear cells (PBMNCs) in the presence of soluble receptor activator of NFkappaB ligand (sRANKL) and macrophage colony-stimulating factor (M-CSF). We show that human osteoclast formation is enhanced when PBMNCs are cultured in the presence of transforming growth factor (TGF)-beta and M-CSF prior to the addition of sRANKL. The effect was only observed in the presence of a nonadherent lymphocyte PBMNC fraction. Osteoclast formation was enhanced to a level equivalent to that induced by TGF-beta when nonadherent PBMNC fraction was removed from the cultures, prior to RANKL treatment. These data suggest that TGF-beta enhances osteoclast formation by abrogating the suppressive effect of the nonadherent PBMNCs, thereby maintaining the osteoclast-forming potential of the osteoclast precursor population. TGF-beta was without effect on proliferation of the adherent PBMNCs and did not stimulate osteoclast size or modify their immunophenotype. The effect was not mediated through prostaglandin synthesis. These results indicate that the microenvironment encountered by the osteoclast precursor prior to RANKL exposure contributes significantly to the regulation of osteoclast formation. Furthermore, the data emphasize that the effect of TGF-beta is determined by the cytokine milieu of the microenvironment and/or the state of activation of the cell being targeted by TGF-beta; thus, the effect of TGF-beta is context-dependent.

Carrier Proteins↗
PubMed2001

Interleukin-4 and interleukin-13: bidirectional effects on human osteoclast formation.

Osteoclasts are cells that resorb bone; they derive from macrophage colony-stimulating factor (M-CSF)-dependent hematopoietic precursors in the presence of soluble activator of NFkappaB ligand (sRANKL). Because transforming growth factor (TGF)-beta, a macrophage deactivator, enhances osteoclast formation we hypothesized that interleukin (IL)-4 and IL-13, also macrophage deactivators, should exert a similar effect. However, IL-4 and IL-13 have been reported as suppressors of murine osteoclast formation. In contrast to the effect of these molecules on murine osteoclast formation, IL-4 and IL-13 were found to be powerful inducers of osteoclast formation and bone resorption when added to human peripheral blood mononuclear cell (PBMC) cultures for 4 days. This stimulatory effect was only observed in cultures containing nonadherent PBMCs. In contrast, both molecules significantly suppressed osteoclast formation in lymphocyte-depleted cultures. These data demonstrate that the cytokine milieu and/or state of cell activation determines how cells of the osteoclast precursor respond to IL-4 and IL-13.

Antineoplastic Agents↗
PubMed2001

Generation of human osteoclasts in stromal cell-free and stromal cell-rich cultures: differences in osteoclast CD11c/CD18 integrin expression.

Osteoclasts form in the presence of macrophage colony-stimulating factor (M-CSF) and receptor activator of Nfkappab ligand (RANKL), a membrane-bound differentiation factor that is now available as a soluble recombinant molecule. Acquisition of the osteoclast phenotype [the alphavbeta3 subunit of the vitronectin receptor (VNR)-, calcitonin receptor (CTR)- and F-actin ring-positive cells] is associated with loss of monocyte/macrophage-associated integrins, specifically CD11b, CD11c and CD18. We hypothesized that differences in the osteoclast integrin adhesion molecule profile may exist in osteoclasts generated in stromal cell-rich and in stromal-free conditions. Unlike osteoclasts generated in vivo, F-actin ring-positive (resorbing) osteoclasts formed in soluble RANKL in vitro, in the absence of stromal cells, and co-expressed CD11c and CD18. However, when osteoclasts were generated from peripheral blood mononuclear cells (PBMNCs) in co-cultures with the murine bone marrow stromal cell line 218 (which does not produce membrane-bound RANKL) in the presence of soluble RANKL, CD11c and CD18 were not expressed by osteoclasts. These findings indicate that the persistent expression of CD11c and CD18 is not accounted for by RANKL being presented in a soluble form and that membrane-bound RANKL is not required for the normal integrin expression in resorbing osteoclasts. This study demonstrates that potentially misleading information may arise by using data obtained from osteoclasts generated in the absence of stromal cells as they do not completely reflect the situation in vivo.

Actins↗
PubMed2001

Investigation of ethnic neutropenia by assessment of bone marrow colony-forming cells.

Healthy individuals with African ancestry have lower neutrophil counts than Caucasians. It has previously been postulated that this was consequent on either a diminished bone marrow granulocyte reserve or an altered distribution of neutrophils between the circulating and marginated granulocyte pools. Recent indirect evidence supports the former hypothesis. In this study we have compared the number of granulocyte plus granulocyte-macrophage colony-forming units (CFUs) in the bone marrow of healthy African and Afro-Caribbean subjects with the number of CFUs in the bone marrow of healthy age and sex-matched Caucasians. We found the group with African ancestry to have significantly fewer CFUs than the Caucasian group. There was no evidence of any qualitative difference between the CFUs of the two ethnic groups: they showed similar sensitivity to granulocyte-monocyte colony stimulating factor and similar enhancement of growth when cultured with a larger range of cytokines. These observations suggest that ethnic neutropenia observed in those with African ancestry is likely to result from reduced numbers of bone marrow progenitor cells in comparison with numbers present in Caucasians.

Adolescent↗
PubMed2000

Bronchopulmonary and mediastinal leishmaniasis: an unusual clinical presentation of Leishmania donovani infection.

We describe a case of unusual leishmaniasis in a Sudanese man with a history of progressively enlarging granulomatous mediastinal lymphadenopathy, worsening hemoptysis, and an intense mucosal granulomatous inflammatory response in the large bronchi. Leishmania donovani DNA was detected in bronchial biopsies by polymerase chain reaction. This is a novel description of human leishmanial infection in an immunocompetent patient involving this anatomical site. The patient's condition improved clinically, spirometrically, and radiologically after a course of treatment with amphotericin B. The cell-mediated immune response was analyzed before, during, and after successful antileishmanial chemotherapy.

Adult↗