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DNA Index (dna + index)

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Medical Sciences	100%

Selected Abstracts

DNA Index in childhood acute lymphoblastic leukaemia: a karyotypic method to validate the flow cytometric measurement

INTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY, Issue 3 2010
P. RACHIERU-SOURISSEAU
Summary The DNA index (DI) is a prognostic factor in childhood acute lymphoblastic leukemia (ALL). The accuracy of DI measurement is important for treatment stratification: hyperdiploidy with DI , 1.16 is predictive of favorable prognosis whereas hypodiploidy is associated with poor prognosis. The aim of this study was to validate the accuracy of the DI measured by flow cytometry (FCM) by comparison with the karyotype. From samples of 112 childhood ALL, we created a formula to calculate a theoretical DNA index (tDI) based on the blast cell karyotype, taking into account the additional or missing chromosome material of the major clone. FCM DI correlated with tDI calculated from karyotype (R = 0.987) and with modal chromosome number (DI = 0.0202 × Modal NB + 0.0675 and R = 0.984). In three cases a hypodiploid blast cell population was detected by FCM, while only the duplicated clone was identified by the karyotype. The strong correlation between tDI and DI validates the accuracy of FCM quantification, which is technically fast on fresh or frozen samples. If the karyotype is essential to analyze chromosomal abnormalities, FCM provides complementary information in aneuploid ALLs, either by confirming the cytogenetic data or by detecting additional clones not identified when only using cytogenetic data. [source]

Near-diploid and near-triploid human sporadic colorectal adenocarcinomas differ for KRAS2 and TP53 mutational status

GENES, CHROMOSOMES AND CANCER, Issue 2 2003
Walter Giaretti
Mutations of the KRAS2 protoncogene and inactivation of the TP53 oncosuppressor gene have been suggested to contribute to chromosomal instability (CIN) and aneuploidy in colorectal cancer (CRC). Previous work has also shown that the degree of DNA ploidy [DNA index (DI)], as obtained by flow cytometry in CRC, is non-randomly distributed and, in particular, that DI near-diploid and near-triploid values are well separated by a low-probability valley region. At present, it is not known whether a relationship exists between DI and the mutational status of KRAS2 and TP53. Multiple samples obtained from 35 human sporadic CRCs have been used to provide nuclei suspensions for flow cytometric analysis and sorting of specific DI subpopulations. Sorted nuclei were then used to analyze the high-microsatellite-instability (MSI-H) phenotype and the mutation spectrum of the KRAS2 and TP53 genes. A single MSI-H case was detected. There were 6 DNA diploid (DI = 1) and 29 aneuploid (DI , 1) CRCs, with the DI aneuploid cases non-randomly subdivided in 9 near-diploid (DI , 1 and DI , 1.4), 8 near-triploid (1.4 < DI < 1.6), and 12 high-aneuploid (DI , 1.6) cases. Proximal CRCs were more often DNA diploid and near-diploid than distal ones, and Dukes' C cases were more commonly high-aneuploid than Dukes' B. Moreover, the incidence of mutations of the KRAS2 and TP53 genes was lowest among the DNA near-triploid subpopulations and highest among the near-diploid ones. We suggest that DNA near-diploid and near-triploid subpopulations in human sporadic CRC reflect different genetic mechanisms of CIN and have a potentially different clinical behavior. © 2003 Wiley-Liss, Inc. [source]

Flow cytometry in breast cancer: cell yield using two different fine needle aspiration devices

INTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 9 2005
R. Freitas Júnior
Summary The aim of the study was to compare the quality of breast aspirates obtained by two methods of fine needle aspiration cytology (FNAC): the auto-vacuum device and the syringe pistol holder, using flow cytometry. Both techniques were used in 44 fresh surgical specimens. Subsequently, these specimens were fixed and mounted in paraffin. Both the aspirates and the de-waxed histology material were prepared for flow cytometry using a FACScan. Flow cytometry showed that the means for DNA index and S-phase fraction were similar for aspirates obtained with both techniques. Mean aneuploidy was significantly higher in the auto-vacuum device aspirates than in the surgical specimen (43.4 SD ± 23 vs. 27.9 SD ± 17; p = 0.04). Mean DNA index and S-phase fraction were similar in cells from aspirates and surgical specimens. It is concluded that both FNAC methods are of similar efficacy in collecting aspirates for flow cytometry. [source]

DNA Index in childhood acute lymphoblastic leukaemia: a karyotypic method to validate the flow cytometric measurement

S-phase fraction and DNA ploidy in oral leukoplakia

ANZ JOURNAL OF SURGERY, Issue 7-8 2010
Rahul Khanna
Abstract Background:, The risk of malignant conversion in oral leukoplakia is well documented. Histological findings are often unreliable and it is difficult to predict on the basis of clinical and histopathological changes which leukoplakic lesion will turn malignant. Methods:, We used the technique of flow cytometry to evaluate the ploidy status, DNA index and S-phase fraction in leukoplakia, oral cancer and normal oral mucosal biopsies and compared it with histological findings. The study was carried out on 30 patients with oral cancer, 60 with leukoplakia and 30 with normal oral mucosal biopsies. Results:, The aneuploidy rate in oral cancers was 64%, for leukoplakia 20%, while all normal mucosal biopsies were diploid. Aneuploid lesions also had a greater S-phase fraction (SPF). The DNA Index (DI) of aneuploid oral cancers was 1.72 and aneuploid leukoplakias was 1.24. Leukoplakia specimens which showed histological evidence of dysplasia had aneuploidy rate of 38%, DI of 1.19 and SPF of 6.2%. The corresponding values for leukoplakia specimens without dysplasia were 14%, 1.09 and 4.1%, respectively. Conclusion:, The method of flow cytometry can be used to identify the subset of leukoplakia patients who are at a higher risk of malignant conversion. These patients could undergo more rigid surveillance or undergo excision biopsy of their lesions. [source]