Biomedical subjects

C N Luckey

Publications and source records attributed to C N Luckey.

5 recordsLinked to original sources

PubMed1999

TrkB isoforms with distinct neurotrophin specificities are expressed in predominantly nonoverlapping populations of avian dorsal root ganglion neurons.

Alternative splicing of the avian trkB receptor generates an extracellular deletion (ED) isoform missing 11 amino acids from the neurotrophin-binding domain of the full-length (FL) receptor. When expressed in fibroblasts, the ED isoform exhibited restricted neurotrophin specificity compared with that of the FL receptor. Brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4) activated the FL receptor, as determined by tyrosine phosphorylation. However, only BDNF was capable of significant activation of the ED isoform, although to a reduced level. Because positively charged residues in NT-3 are important for binding to trkB, two negatively charged aspartate residues within the 11 amino acid motif of FL trkB were mutated to examine the role of electrostatic interactions on ligand binding. As found for the ED isoform, the FL mutated receptor displayed a similar loss of NT-3- and NT-4-mediated activation, in addition to a diminished responsiveness to BDNF. Because of these profound effects on ligand specificity, reverse transcription-PCR was used to understand the expression of the FL and ED receptor isoforms at the level of single neurons. The predominant expression pattern of either FL or ED isoforms in single embryonic DRG neurons establishes the existence of two subpopulations exhibiting differential responsiveness to trkB ligands, indicating that regulated splicing of the extracellular domain of trkB may serve as a mechanism to restrict neuronal responsiveness to the neurotrophins.

Alternative Splicing↗

PubMed1995

Breakpoint cluster region, immunoglobulin, and T-cell receptor gene rearrangement analysis in juvenile chronic myelogenous leukemia.

Juvenile chronic myelogenous leukemia (JCML) is a heterogeneous disorder composed of Philadelphia chromosome-positive (Ph+) CML, which is similar to CML in adults, and Ph-negative (Ph-) CML, a childhood myelodysplasia resembling chronic myelomonocytic leukemia in adults. These two disorders are not always readily separable by leukocyte alkaline phosphatase (LAP) scoring and by karyotyping, yet they have different courses and outcomes. We compared the results of breakpoint cluster region (bcr) gene rearrangement analysis with LAP score and karyotype in these patients. In addition, analysis for immunoglobulin and T-cell receptor gene rearrangement was done to investigate the possibility of mixed myeloid and lymphoid lineage, which has been shown to occur in childhood acute myelogenous leukemia and CML in blast crisis. Peripheral blood and bone marrow samples from six patients with JCML aged 5 to 19 yr were analyzed. One case was Ph+, and five were Ph- by karyotyping. Two samples showed LAP scores of 5 and 11 (one Ph+ and one Ph-); others were normal. All were digested with EcoRI, HindIII, and BamHI for immunoglobulin heavy and light chains and T-cell receptor beta-chain analysis and, in addition, with BglII for bcr analysis. Samples were hybridized with probes to JH, JK, CT beta, and bcr (Oncor). A bcr rearrangement was shown in the Ph+ sample; all others, including one with a very low LAP score, were negative. No JH, JK, or CT beta rearrangements were detected.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1994

Improved diagnostic accuracy in needle biopsy interpretation using molecular probes.

A prospective study of computed tomographically guided core needle biopsy samples was done to determine whether diagnostic accuracy could be improved in these specimens. Eighteen specimens from 16 patients were analyzed by routine and immunohistochemical stains on paraffin-embedded tissue and DNA probe hybridization on frozen tissue. Pathologic diagnoses based on light microscopy and immunostaining were malignant lymphoma (8), lymphoid tissue (1), malignant tumor (3), fibrous tissue (2), fatty liver and hepatic adenoma (2), giant cell tumor (1), and necrotic tissue (1). Analyzable DNA was obtained from nine specimens (50%); 67% of those yielding insufficient DNA (six of nine) were samples of benign liver, connective tissue, and necrotic tissue. Extracted DNA was hybridized with probes for JH, JK, CT beta, and bc/II. In 67% of analyzable cases (six of nine) the diagnosis of lymphoma was confirmed; in 33% the diagnosis of lymphoma or nonlymphoma was aided or resolved when the pathologic diagnosis was uncertain. Of the eight cases of lymphoma diagnosed by light microscopy, six were confirmed by genotyping and two yielded insufficient DNA for analysis. In all nine cases with sufficient DNA, hybridization identified B-cell monoclonality and confirmed or excluded follicular center cell origin, data not uniformly obtained with other studies. Molecular analysis can be a useful adjunct to routine methods of diagnosis of needle specimens, improving diagnostic accuracy in at least one-third of cases.

Adult↗

PubMed1993

Monoclonality in reactive lymphadenopathy: gene rearrangement and multiparameter analysis.

Multiparameter analysis of lymph nodes with follicular, interfollicular, and/or atypical hyperplasia was undertaken to search for monoclonality. Twenty-three patients aged 7 to 75 years (mean 32 years) were studied. One patient had a history of lymphoma; two were HIV-positive. Nodes were removed for clinical suspicion of lymphoma. Light microscopy revealed increased and&or abnormal follicular proliferation and occasional progressive transformation of germinal centers. Immunostaining of frozen sections revealed CD4, CD8, kappa, and lambda positivity with more CD4+ than CD8+ cells. Flow cytometry showed a mixed population of T and B cells with no evidence of clonality. Hybridization studies with JH and JK probes showed rearranged bands in one case. No rearrangements were seen with CT beta and bcl-2 probes. Follow-up of 3 to 5 years showed no new occurrences of lymphoma. Although no evidence of monoclonality was seen with other parameters, DNA hybridization revealed heavy and light chain gene rearrangement in 4% (1 of 23).

Adolescent↗

PubMed1991

Prospective gene rearrangement studies and multiparameter analysis of acute myeloid leukemia.

Twenty-six cases of acute myeloid leukemia (AML) with cytochemical and immunophenotypic data were studied prospectively for immunoglobulin and T-cell receptor gene rearrangement. Dysmyelopoiesis was seen in 100% and Auer rods in 18%. Sudan black B was positive in 83% of the cases, peroxidase in 76%, nonspecific esterase in 74% (fluoride-inhibited in 82%), chloroacetate in 70%, acid phosphatase and PAS in 100%, and immunoperoxidase stains for platelet glycoprotein IIIa and factor VIII in 0% of the cases studied. Flow cytometry revealed myeloid phenotype in 19 of 20 cases. In four cases 5-86% of cells were TdT positive. Heavy-chain gene rearrangement was demonstrated in three cases (12%) and kappa light chain gene rearrangement in one; clinically significant rearrangement of the T-cell receptor gene was not found. Rearrangements of immunoglobulin genes are found occasionally in AML; these may represent nonspecific findings or coexistent lymphoid differentiation in AML.

Adolescent↗