 Dr. Leonard and his staff conduct applied research to ensure that cytogenetic analyses for the CCR meet the best and most current standards of practice. They are also involved in data mining of the CCR's extensive set of cytogenetics data. Basic research interests include the maintenance of chromosome integrity and the consequences of failure in chromosome instability syndromes and during the aging process.
In addition, the laboratory's studies of DNA misrepair in chromosomes further enhances efforts to understand cancer.
Current research endeavors in the Cytogenetics Laboratory include:
- use of spectral karyotyping to improve the analysis of human and mouse cultures by multicolor chromosome painting of nonhuman primate cultures by cross species painting
- use of a CGH, microarray Comparative Genomic Hybridization analysis to better identify the chromosome segments involved in structural rearrangements, especially partial aneuploidies (losses or gains) and ultimately their relationship to human disease
- investigation of the relationship of the breakdown in chromosome integrity to the aging process
- evaluation of the relationship between spontaneous aberration frequencies in cultured cells and the number of population doublings in vitro
- analysis of the patterns of spontaneous chromosome aberrations in cultures associated with the GRC Baltimore Longitudinal studies*
*Examination of the cellular response to genetic damage by studies of chromosome aberrations
Dr. Leonard earned a Ph.D. from the Department of Human Genetics in the School of Basic Sciences of the Medical College of Virginia in 1981, where he investigated the radiation sensitivity associated with the Down syndrome phenotype. Following those studies, he spent a year as a post-doctoral fellow in the Radiobiology Groups of the Oncology Center of The Johns Hopkins University, where his work focused on differential radiation resistance in particular cells.
In 1982, he joined Dr. Michael Benders group in the Medical Department of the Brookhaven National Laboratory as an Assistant Scientist, where the group attempted to identify the range of normal sensitivity to model genotoxic agents through assays of chromosome damage and DNA repair. During this time, Dr. Leonard also conducted studies of common fragile site induction.
In 1987, Dr. Leonard left Brookhaven to become the Cytogenetics Laboratory Director of the Wilson Genetics Center, where his laboratory specialized in prenatal diagnosis. During his tenure, he introduced the techniques of image analysis and fluorescence in situ hybridization (FISH) into the laboratory routine. At that time, he was also an Adjunct Assistant Professor in the Program for Genetics. In 1990, he became a Diplomat of the American Board of Medical Genetics in Clinical Cytogenetics. From 1991 through 1992 he directed the Cytogenetics Laboratory in the Pediatrics Department of the Albert Einstein Medical Center in Philadelphia, Pennsylvania. In 1992, Dr. Leonard joined the scientific staff of the Coriell Cell Repositories to direct the activities of its Cytogenetics Laboratory.
Representative Publications
Markov V, Kusumi K, Tadesse MG, William DA, Hall DM, Lounev V, Carlton A, Leonard J, Cohen RI, Rappaport EF, and Saitta B
Identification of Cord Blood-Derived Mesenchymal Stem/Stromal Cell Populations with Distinct Growth Kinetics, Differentiation Potentials, and Gene Expression Profiles.
Stem Cells Dev 16: Feb #1 in press 2007
Lynn E, DeLisi LE, Maurizio AM, Svetina C, Ardekani B, Nierenberg J, Szulc K, Leonard J, Harvey PD
Klinefelter syndrome (XXY) as a genetic model for psychotic disorders.
Am J Hum Genet Neuropsychiatric Genetics (in press).
PMID: 11484199 abstract
Shanske A, Ferreira JC, Leonard JC, Fuller P, Marion RW
Hirschsprung disease in an infant with a contiguous gene syndrome of chromosome 13.
Am J Med Genet 102(3):231-6, 2001.
PMID: 11484199 abstract
Lee I, Lee J, Lee YH, Leonard JC
Irsolic acid-induced changes in tumor growth, O2 consumption and tumor interstitial fluid pressure.
Anticancer Res. 21(4A):2827-33, 2001.
PMID: 11724362 abstract
Leonard, JC, Toji, LH, Bender PK, Beiswanger, CM, Beck, JC, Johnson, RT
Regional Mapping Panels for Human Chromosomes 1, 2, and 7.
Somatic Cell and Molecular Genetics 25(4):247-251, 2001.
Leonard JC, Toji LH, Bender PK, Beiswanger CM, Beck JC, Johnson RT
Panel description. Regional mapping panels for chromosomes 6, 9, and 16.
Genomics 58(3):323-6, 1999.
PMID: 10373332; UI: 99303565 abstract
full text
Leonard JC, Toji LH, Bender PK, Beiswanger CM, Beck JC
Regional mapping panels for chromosomes 8, 13, 21, and 22.
Genomics 51(1):17-20, 1998.
PMID: 9693028; UI: 98360087 abstract
full text
Xu YS, Overton WR, Marmar JL, Leonard JC, McCoy JP Jr, Butler GH, Li H
Complete replication of human sperm genome in egg extracts from Xenopus laevis.
Biol Reprod 58(3):641-7, 1998.
PMID: 9510951; UI: 98171940 abstract
Leonard JC, Drwinga HL, Kim CH, Toji LH, Bender PK, Mulivor RA, Beck JC
Regional mapping panels for chromosomes 3, 4, 5, 11, 15, 17, 18, and X.
Genomics 46(3):530-4, 1997.
PMID: 9441767; UI: 98110599 abstract
Silverman GA, Schneider SS, Massa HF, Flint A, Lalande M, Leonard JC, Overhauser J, van den Engh G, Trask BJ
The 18q- syndrome: analysis of chromosomes by bivariate flow karyotyping and the PCR reveals a successive set of deletion breakpoints within 18q21.2-q22.2.
Am J Hum Genet 56(4):926-37, 1995.
PMID: 7717403 abstract
Wise JP, Leonard JC, Patierno SR
Clastogenicity of lead chromate particles in hamster and human cells. Mutat Res 278(1):69-79, 1992.
PMID: 1370121 abstract
Jorgensen TJ, Leonard JC, Thraves PJ, Dritschilo A
Baseline sister chromatid exchange in human cell lines with different levels of poly(ADP-ribose) polymerase.
Radiat Res 127(1):107-10, 1991.
PMID: 1906188 abstract
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