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Biomedical subjects

Patrick J Leavey

Publications and source records attributed to Patrick J Leavey.

11 recordsLinked to original sources
PubMed2007

Extracorporeal membrane oxygenation (ECMO) initiation without intubation in two children with mediastinal malignancy.

We report the cases of two children presenting with severe airway compromise secondary to a mediastinal malignancy managed with extracorporeal membrane oxygenation without intubation. Results are presented on the use of ECMO as a primary means of stabilizing a pediatric patient with a critical mediastinal mass, thus providing another management strategy for this difficult situation.

Antineoplastic Agents↗
PubMed2004

Phase I study of oral cyclophosphamide and oral topotecan for children with recurrent or refractory solid tumors.

BACKGROUND: To determine the maximum-tolerated duration and dose-limiting toxicity of a daily schedule of orally administered cyclophosphamide and topotecan in pediatric patients with recurrent or refractory malignant solid tumors. METHODS: Patients received oral cyclophosphamide (50 mg/m2/dose) in the morning followed by topotecan (0.8 mg/m2/dose) 8-12 hr later for an escalating number of consecutive days (10, 14, and 17 days). RESULTS: Seventeen pediatric patients were treated with oral cyclophosphamide and topotecan for durations of 10-17 days for a total of 58 treatment courses. Reversible hematologic toxicity (neutropenia and thrombocytopenia) was the dose-limiting toxicity. Nonhematologic toxicities of greater than grade 3 were not observed. A partial response (neuroblastoma following myeloablative chemotherapy and stem cell rescue) and prolonged stable disease (medulloblastoma) were each observed in one patient. CONCLUSIONS: The recommended duration of therapy with a daily schedule of both oral cyclophosphamide (50 mg/m2/day) and topotecan (0.8 mg/m2/day) for previously treated pediatric patients with recurrent or refractory solid tumors is 14 consecutive days. The observed dose limiting toxicity (DLT) was reversible neutropenia. This regimen was well tolerated in heavily pretreated patients and demonstrated activity against recurrent pediatric solid tumors.

Administration, Oral↗
PubMed2003

Cyclooxygenase-2 expression does not correlate with outcome in osteosarcoma or rhabdomyosarcoma.

PURPOSE: To determine if expression of cyclooxygenase (COX)-2, an inducible enzyme with known tumor-promoting activity, correlates with outcome in pediatric sarcomas. COX-2 overexpression correlates with more aggressive disease in a variety of adult solid tumors. METHODS: Archived human osteosarcoma, rhabdomyosarcoma, and Ewing sarcoma tumors were retrospectively evaluated, blinded to outcome, for COX-2 expression by immunohistochemistry and correlated with patient characteristics and survival. RESULTS: COX-2 expression was detected in 94 of 142 (66%) tumors (osteosarcoma, 66/99 [67%]; rhabdomyosarcoma, 21/35 [60%]; Ewing sarcoma, 7/8 [88%]) and 51 of 85 (60%) diagnostic biopsies (osteosarcoma, 26/45 [58%]; rhabdomyosarcoma, 21/35 [60%]; Ewing sarcoma, 4/5 [80%]). COX-2 expression did not vary with clinicopathologic features and was not predictive of prognosis in these cases. CONCLUSIONS: This study does not support the use of COX-2 expression as an upfront prognostic variable in patients with osteosarcoma or rhabdomyosarcoma. Results from the small number of patients studied with Ewing sarcoma suggest a similar lack of predictive value for COX-2 expression. However, COX-2 inhibitors are not entirely dependent upon enzyme expression for their antitumor effects; this study does not necessarily preclude the use of COX-2 inhibitors for the treatment of pediatric sarcomas.

Adult↗
PubMed2003

The epidermal growth factor receptor HER2 is not a major therapeutic target in Ewing sarcoma.

BACKGROUND: Although chimeric EWS gene and Ets gene fusions are pathognomonic of Ewing sarcoma (ES) and primitive neuroectodermal tumors (PNET), the molecular pathogenesis of these pediatric malignancies is poorly understood. Recently, the human epidermal growth factor (HER)-2 receptor, which plays an important role in the biology of certain epithelial cancers, has been implicated in ES tumor cell line growth and chemosensitivity. MATERIALS: To investigate whether HER2 might be a rational target for ES/PNET therapy, five ES cell lines and 13 archival primary ES/PNET samples were examined by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) for evidence of HER2 overexpression. RESULTS: Although several ES cell lines demonstrated modest constitutive HER2 expression by immunoblot, none of the ES cell lines or primary tumor samples showed evidence of HER2 overexpression by IHC or HER2 gene amplification by FISH. Moreover, treatment of human ES cell lines with the HER2-targeted agent trastuzumab (Herceptin) had little effect on cell survival, proliferation, or growth in semi-solid medium. CONCLUSIONS: These results suggest that HER2 is not a biologically or therapeutically important pathway in ES/PNET.

Antibodies, Monoclonal↗
PubMed2003

Skip metastasis in osteosarcoma.

Skip metastasis is rare in high-grade osteosarcoma and indicates a very poor prognosis. The authors describe two patients who had high-grade osteosarcoma and skip metastasis. MRI detected the skip lesion in both patients, and both lesions were confirmed by histology. The patients were treated with adjuvant chemotherapy and radical surgical resection. Both are alive and free of disease 3 and 6 years from diagnosis.

Adolescent↗
PubMed2002

Effective removal of methotrexate by high-flux hemodialysis.

The purpose of the present study was to examine the clearance of methotrexate (MTX) by high-flux hemodialysis (HD) in pediatric oncology patients. We present three patients who experienced nephrotoxicity and prolonged exposure to toxic MTX concentrations following high-dose infusions during treatment for osteogenic sarcomas. Each patient was successfully treated with high-flux HD, followed by carboxypeptidase G2 (CPDG2) in two cases. Minimal systemic toxicity occurred. We review the literature and discuss guidelines for early and aggressive treatment for this complication of high-dose MTX therapy. Clinically important removal of MTX depends upon prompt initiation of HD after detection of nephrotoxicity and delayed clearance of MTX. Therapy is indicated in cases where compassionate use of CPDG(2) may not be available, or while awaiting its delivery.

Adolescent↗
PubMed2002

A 29-kDa protein associated with p67phox expresses both peroxiredoxin and phospholipase A2 activity and enhances superoxide anion production by a cell-free system of NADPH oxidase activity.

Production of toxic oxygen metabolites provides a mechanism for microbicidal activity of the neutrophil. The NADPH oxidase enzyme system initiates the production of oxygen metabolites by reducing oxygen to form superoxide anion (O(2)()). With stimulation of the respiratory burst, cytosolic oxidase components, p47(phox), p67(phox), and Rac, translocate to the phagolysomal and plasma membranes where they form a complex with cytochrome b(558) and express enzyme activity. A 29-kDa neutrophil protein (p29) was identified by co-immunoprecipitation with p67(phox). N-terminal sequence analysis of p29 revealed homology to an open reading frame gene described in a myeloid leukemia cell line. A cDNA for p29 identical to the open reading frame protein was amplified from RNA of neutrophils. Significant interaction between p29 and p67(phox) was demonstrated using a yeast two-hybrid system. A recombinant (rh) p29 was expressed in Sf9 cells resulting in a protein with an apparent molecular weight of 34,000. The rh-p29 showed immunoreactivity with the original rabbit antiserum that detected p47(phox) and p67(phox). In addition, rh-p29 exhibited PLA(2) activity, which was Ca(2+) independent, optimal at low pH, and preferential for phosphatidylcholine substrates. The recombinant protein protected glutathione synthetase and directly inactivated H(2)O(2). By activity and sequence homology, rh-p29 can be classified as a peroxiredoxin. Finally, O(2)() production by plasma membrane and recombinant cytosolic oxidase components in the SDS-activated, cell-free NADPH oxidase system were enhanced by rh-p29. This effect was not inhibited by PLA(2) inhibitors. Thus, p29 is a novel protein that associates with p67 and has peroxiredoxin activity. This protein has a potential role in protecting the NADPH oxidase by inactivating H(2)O(2) or altering signaling pathways affected by H(2)O(2).

Animals↗
PubMed2002

In vivo treatment with granulocyte colony-stimulating factor does not delay apoptosis in human neutrophils by increasing the expression of the vacuolar proton ATPase.

BACKGROUND: Neutrophils die by apoptosis, and in vivo administration of granulocyte colony-stimulating factor (G-CSF) delays this apoptotic cell death. G-CSF administered in vitro correlates delayed apoptosis with upregulation of the vacuolar proton ATPase (v-ATPase). Because this enzyme requires assembly of membrane and cytosolic domains to function, we hypothesized that in vivo G-CSF would increase synthesis and assembly of v-ATPase components to delay apoptosis. METHODS: Volunteers received G-CSF for 5 days, and each had a paired control. Neutrophils were isolated from subjects before the first and after the fifth injection. Proteins from cytosol or plasma membrane or from whole cell lysates were resolved by SDS-polyacrylamide gel electrophoresis and immunoblotted with antibody to the 33kDa v-ATPase E subunit. Densitometry quantified immunoreactivity. RESULTS: No significant increase on the E subunit occurred between treated and control groups. CONCLUSION: In vivo G-CSF does not increase the amount of v-ATPase in neutrophils. Although G-CSF in vivo delays apoptosis, the mechanism(s) by which this occurs is not known.

Adult↗
PubMedDate not supplied

Variability in dose intensity of high-dose methotrexate for nonmetastatic osteosarcoma.

The authors evaluated their ability to maintain planned dosing schedules for high-dose methotrexate (HD-MTX) in patients with nonmetastatic osteosarcoma. Twenty-seven patients who received therapy according to 2 POG protocols (8651 and 9351), both of which included HD-MTX (12 g/m(2)/week for 2 consecutive weeks), between 1988 and 1998 were studied. Significantly fewer HD-MTX infusions were given on the second week to patients treated on POG 9351 (33 vs. 93%; p < .0001). The hydration guidelines were identical and there was no difference in peak serum MTX levels either within or between protocols. Differences in the administration of combination chemotherapy in 9351 compared to 8651 may have contributed to the increased toxicity associated with HD-MTX on 9351, although this is speculative. The use of HD-MTX should be carefully planned so that it does not decrease its dose intensity or that of other effective agents.

Antimetabolites, Antineoplastic↗
PubMedDate not supplied

KAI-1 expression in pediatric high-grade osteosarcoma.

Recent evidence implicates cell surface proteins of the tetraspanin superfamily in the process of metastasis whereas the downregulation of KAI-1, a member of the tetraspanin family, is associated with an aggressive clinical phenotype in several types of human cancers. To determine if expression of KAI-1-1 is associated with any known prognostic marker or clinical outcome in high-grade osteosarcoma, we examined 91 nondecalcified archival samples from 47 patients for the expression of KAI-1. Archival, paraffin-embedded, and decalcified pathologic samples were examined by immunohistochemistry and results were correlated to clinical outcomes and known prognostic markers. There were 46 samples from diagnostic biopsies (1 diagnostic sample was not available), 32 tumor resection samples, and 13 metastasis samples. Thirty-three percent (n=30) of the samples expressed KAI-1 (16 biopsies, 9 resections, and 5 metastasis). KAI-1 expression was not significantly related to known prognostic markers or to either tumor necrosis after neoadjuvant therapy or the incidence of metastasis at diagnosis. KAI-1 expression was not significantly different between paired diagnostic tumor samples and either resection or metastasis tumor samples. Twenty-five patients remain alive at a median follow-up of 95 months. The overall and progression-free survival percentages at 5 years were 62% and 47% for KAI-1-positive patients and 49% and 38% for KAI-1-negative patients, respectively. This difference was not statistically significant. We conclude that KAI-1 is expressed in a proportion of high-grade osteosarcoma but is not of clinical significance and cannot be used to stratify treatment groups for these patients.

Adjuvants, Immunologic↗