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PubMed1987

Identification of protein antigens associated with the nuclear matrix and with clusters of interchromatin granules in both interphase and mitotic cells.

Monoclonal antibody 3C5 recognizes a family of protein antigens present predominantly within the nucleus of interphase cells. We have shown previously that the epitope recognized by 3C5 is phosphorylated and have concluded that the proteins defined by this antibody share a common phosphorylation site. Using a combination of immunofluorescence microscopy and immunogold labelling in conjunction with electron microscopy, we have studied the distribution of 3C5-reactive material within interphase and mitotic cells. Antibody 3C5 was found to label specific structures within the interphase nucleus that, on the basis of their characteristic granulofibrillar morphology and strong staining with bismuth, have been identified as clusters of interchromatin granules (IG clusters). Double-labelling experiments with 3C5 and monoclonal antibodies to DNA have shown that these structures contain no detectable DNA. However, by indirect immunofluorescence, we have shown that 3C5-reactive nuclear structures do label with human autoantibodies to the Sm antigen, a component of small nuclear RNP particles (snRNPs). Granulofibrillar structures that stained strongly with bismuth, and were morphologically identical to nuclear IG clusters, were observed in the cytoplasm of mitotic cells. These structures also labelled with 3C5 but not with anti-Sm antibodies. Our results suggest that IG clusters remain essentially intact through mitosis though some snRNP components are apparently lost. In situ extraction of cultured cells with Triton X-100, micrococcal nuclease and 1-2M-NaCl failed to deplete 3C5-reactive material in either interphase or mitotic cells, though some redistribution was evident. In addition, 3C5-reactive proteins were identified in nuclear matrices prepared from rat liver by high-salt extraction procedures. However, the recovery of such proteins was strongly influenced by the preparation technique employed. Our results suggest that 3C5-reactive proteins and IG clusters are anchored to, but not integral components of, salt-resistant structural elements of the interphase nucleus and the mitotic cytoplasm, presumably the nuclear matrix and the cytoskeleton, respectively.

Animals↗

PubMed2004

Comparison of genetic changes between interphase and metaphase nuclei in monitoring CML and APL treatment using DC-FISH technique.

In leukemias, the monitoring techniques on the response after the treatment have clinical importance for evaluating new therapeutic approaches and identifying the risk of relapse. In this study, genetic changes before and after chemotherapy in interphase and metaphase nuclei of bone morrow of adults with provisional diagnosis of leukemia were compared to understand the molecular characterization and pathogenesis of the leukemia for the classification of diagnosis and prognosis. We examined bone morrow cells of 47 chronic myeloid leukemia (CML) cases (29 of 47 at the time of diagnosis, 31 of 47 after chemotherapy) with the bcr/abl translocation probes and of 10 acute promyelocytic leukemia (APL) cases (7 of 10 at the time of diagnosis, 4 of 10 after chemotherapy) with the PML/RARalpha translocation probes by using dual color-flourescence in situ hybridization (DC-FISH). For each case, 400 interphase nuclei and 11 to 25 metaphases nuclei were analysed. The ratios of translocations before and after chemotherapy were compared between interphase and metaphase nuclei. After chemotherapy, though, translocations were detected in interphase nuclei of 29 of the 31 CML and 4 of the 4 APL cases, these translocations were determined in metaphase nuclei of only 14 of the 31 CML and 1 of the 4 APL cases with very low ratios (p < 0.01). The results showed that the rates of translocation positive interphase nuclei were higher than the rates of translocation positive metaphase nuclei (p < 0.01) after chemotherapy, so there may be some factors effecting proliferative activity of metaphase formation in leukemias.

Bone Marrow Cells↗

PubMed1992

Mechanism of radiosensitization by halogenated pyrimidines: effect of BrdU on repair of DNA breaks, interphase chromatin breaks, and potentially lethal damage in plateau-phase CHO cells.

There is evidence suggesting that radiosensitization induced in mammalian cells by substitution in the DNA of thymidine with BrdU has a component that relies on inhibition of repair and/or fixation of radiation damage. Here, experiments designed to study the mechanism of this phenomenon are described. The effect of BrdU incorporation into DNA was studied on cellular repair capability, rejoining of interphase chromosome breaks, as well as induction and rejoining of DNA double- and single-stranded breaks (DSBs and SSBs) in plateau-phase CHO cells exposed to X rays. Repair of potentially lethal damage (PLD), as measured by delayed plating of plateau-phase cells, was used to assay cellular repair capacity. Rejoining of interphase chromosome breaks was assayed by means of premature chromosome condensation (PCC); induction and rejoining of DNA DSBs were assayed by pulsed-field gel electrophoresis and induction and rejoining of DNA SSBs by DNA unwinding. A decrease was observed in the rate of repair of PLD in cells grown in the presence of BrdU, the magnitude of which depended upon the degree of thymidine replacement. The relative increase in survival caused by PLD repair was larger in cells substituted with BrdU and led to a partial loss of the radiosensitizing effect compared to cells tested immediately after irradiation. A decrease was also observed in the rate of rejoining of interphase chromosome breaks as well as in the rate of rejoining of the slow component of DNA DSBs in cells substituted with BrdU. The time constants measured for the rejoining of the slow component of DNA DSBs and of interphase chromosome breaks were similar both in the presence and in the absence of BrdU, suggesting a correlation between this subset of DNA lesions and interphase chromosome breaks. It is proposed that a larger proportion of radiation-induced potentially lethal lesions becomes lethal in cells grown in the presence of BrdU. Potentially lethal lesions are fixed via interaction with processes associated with cell cycle progression in cells plated immediately after irradiation, but can be partly repaired in cells kept in the plateau-phase. It is hypothesized that fixation of PLD is caused by alterations in chromatin conformation that occur during normal progression of cells throughout the cell cycle.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1985

Phosphorylation of the nuclear lamins during interphase and mitosis.

The nuclear lamina is a polymeric protein assembly that is proposed to function as an architectural framework for the nuclear envelope. Previous work suggested that phosphorylation of the major polypeptides of the lamina (the "lamins") may induce disassembly of this structure during mitosis. To further investigate the possible involvement of phosphorylation in regulation of lamina structure, we characterized lamin phosphorylation occurring in mammalian tissue culture cells during interphase and mitosis. Phosphorylation occurs continuously throughout all interphase periods (coordinately with nuclear envelope growth), and takes place mainly on the assembled lamina. When the lamina is disassembled during cell division, the lamins are modified with approximately 1-2 molecules of associated phosphate. This level of mitotic phosphorylation is 4-7-fold higher than the average interphase level. Lamin phosphate occurs predominantly as phosphoserine, and is distributed over numerous tryptic peptides, many of which are modified during both interphase and mitotic periods. Significantly, phosphorylation is the only detectable charge-altering postsynthetic modification of the lamins that occurs specifically during mitosis. The results of this study support the notion that phosphorylation is important for regulation of interphase and mitotic lamina structure.

Amino Acids↗

PubMed1996

Biological dosimetry by interphase chromosome painting.

Both fluorescence in situ hybridization of metaphase spreads with whole-chromosome probes and premature chromosome condensation in interphase nuclei have been used in the past to estimate the radiation dose to lymphocytes. We combined these techniques to evaluate the feasibility of using painted interphase chromosomes for biodosimetry. Human peripheral lymphocytes were exposed to gamma rays and fused to mitotic Chinese hamster cells either immediately after irradiation or after 8 h incubation at 37 degrees C. Interphase or metaphase human chromosomes were hybridized with a composite probe specific for human chromosomes 3 and 4. The dose-response curve for fragment induction immediately after irradiation was linear; these results reflected breakage frequency in the total genome in terms of DNA content per chromosome. At 8 h after irradiation, the dose-response curve for chromosome interchanges, the prevalent aberration in interphase chromosomes, was linear-quadratic and similar to that observed for metaphase chromosomes. These results suggest that painting prematurely condensed chromosomes can be useful for biological dosimetry when blood samples are available shortly after the exposure, or when interphase cells are to be scored instead of mitotic cells.

Animals↗

PubMed1996

Design and validation of DNA probe sets for a comprehensive interphase cytogenetic analysis of acute myeloid leukemia.

The objective of this study was to design DNA probe sets that enable the detection of chromosome aberrations in acute myeloid leukemia (AML) by interphase cytogenetics using fluorescence in situ hybridization (FISH) and to compare the results of interphase cytogenetics with those of conventional chromosome banding analysis. One hundred five consecutive patients with adult AML entered on a multicenter treatment trial were studied with a comprehensive set of DNA probes recognizing the most relevant AML-associated structural and numerical chromosome aberrations: translocations t(8;21), t(15;17), and t(11q23); inversion inv(16);chromosomal deletions (5q-, 7q-, 9q-, 12p-, 13q-, 17p-, and 20q-); and chromosomal aneuploidies. Interphase cytogenetics was particularly sensitive for detecting the AML-specific gene fusions: 3 additional cases of inv(16) and 1 additional case of t(8;21) were identified by FISH that were missed by banding analysis, whereas equal numbers of t(11q23) and t(15;17) were detected. Five additional cases of trisomy 8q, 3 more cases of trisomy 11q, and 2 more cases of trisomies 21q and 22q were shown by FISH. These aberrations were either masked in complex karyo-types or identified in cases in which conventional banding analysis failed. On the other hand, the DNA probes selected were not informative to detect 1 case of 5q-, 9q-, and 20q-. In 5 cases, clonal aberrations were detected on banding analysis for which no FISH probes were selected. In conclusion, interphase cytogenetics proved to be more sensitive for detecting AML-specific chimeric gene fusions and some partial trisomies. Interphase cytogenetics provides a powerful technique complementary and, with further development of diagnostic DNA probes, even an alternative to chromosome banding studies for the cytogenetic analysis of AML.

Acute Disease↗

PubMed1999

[A DNA probe suitable for the detection of chromosome 21 copy number in human interphase nuclei by fluorescence in situ hybridization].

OBJECTIVE: To prepare DNA probe which can be used to accurately detect chromosome 21 copy number in human interphase nuclei by fluorescence in situ hybridization (FISH). METHODS: A probe was produced by universal primer PCR from YAC clone 881D2 and characterized by FISH to metaphases and interphase nuclei of peripheral lymphocytes from 8 normal individuals and 5 patients suffering from trisomy 21. RESULTS: A DNA probe was produced and its characteristics were :(1) Most of the probes ranged in size from 350bp to 750bp; (2) The hybridization signals of the probes were located near centromere on long arm of human chromosome 21; (3) In 1524 metaphases scored, about 99.95% of hybridization signals were located on chromosome 21; (4) The signals were very bright and recognizable easily in both metaphases and interphases nuclei; (5) The expected copy number of chromosome 21 was detected by FISH with the probe in more than 98.40% of interphase nuclei and 99.60% of metaphases. CONCLUSION: The DNA probe reported here is suitable for the detection of chromosome 21 copy number in interphase nuclei and for the study of segregation of chromosome 21 during mitoses of human lymphocytes in culture.

Cell Nucleus↗

PubMed2004

Influence of interphase layer on the overall elasto-plastic behaviors of HA/PEEK biocomposite.

A three-dimensional finite element unit cell model has been designed and constructed for studying mechanical properties of hydroxyapatite (HA) reinforced polyetheretherketone (PEEK) biocomposite. The model consists of an elastic-brittle HA spherical particle, an elasto-plastic matrix and an interphase layer between the particle and the matrix. The interphase layers with four different kinds of material behaviors have been taken into consideration to examine their effects on the overall properties of the composite. The damage evolution in the matrix and the interphase layer, and the interface failure, were also taken into account. Some other factors, such as mesh sensitivity, loading velocity and mass scale scheme, were also discussed in this investigation. A general-purpose finite element software package, ABAQUS, incorporated with a user-defined material subroutine, was used to perform the analysis. The predicted results were compared with the experimental data obtained from existing literatures. The results predicted by using the cell model with consideration of the matrix degradation and the effects of the damage and failure on the interphase layer are in good agreement with the experimental ones. Hence, the suitability of our proposed cell model incorporated with an appropriate type of the interphase layer for modeling the mechanical properties of the particulate biocomposite could be verified.

Benzophenones↗

PubMed1968

RNA synthesis in Chinese hamster cells. I. Differential synthetic rate for ribosomal RNA in early and late interphase.

The incorporation of methionine-methyl-(14)C into 18S ribosomal RNA of cultured Chinese hamster ovary cells in early and late interphase has been determined by zone-sedimentation analysis of phenol-extracted RNA preparations. Synchronized cell cultures were prepared for these studies by thymidine treatment and by mechanical selection of mitotic cells. The specific activity of 18S RNA labeled in late interphase was found to be 1.1-1.2 times that of 18S RNA labeled in early interphase. Upon correction for increase in RNA mass, the rate of methylation of 18S RNA in late interphase is about 1.9 times that in early interphase.

Animals↗

PubMed2006

Interphase evolution in polymer films by confocal Raman microspectroscopy.

Liquid-glassy polymer diffusion is an important topic in polymer physics, with several mechanistic aspects that still remain unclear. Here we describe the use of confocal Raman microspectroscopy (CRM) to study directly several features of interphase evolution in a system of this type. The interphase studied was generated by contact between liquid polystyrene (PS) and glassy polyphenylene oxide (PPO). Interphase evolution on thin films made from these polymers was followed by depth profiling in combination with immersion optics. We also applied regularized deconvolution to improve the spatial resolution of the measurements. With the help of these techniques, we examined interphase PPO concentration profiles and kinetics of interphase evolution in the range 120-180 degrees C, well below the glass transition temperature of the PPO-based films (185 degrees C). Overall, the experiment captures the most important features needed to discern the mechanistic factors that control this process. In this sense, confocal Raman microspectroscopy emerges as one of the best experimental techniques for the study of diffusion kinetics in this type of system.

Membrane Fluidity↗

PubMed2000

Gamma-tubulin distribution in interphase and mitotic cells upon stabilization and depolymerization of microtubules.

Indirect immunofluorescence and digital videomicroscopy were used to study gamma-tubulin distribution in normal mitotic and interphase HeLa cells and after their treatment with microtubule-stabilizing (taxol) and depolymerizing (nocodazole) drugs. In interphase HeLa cells, the affinity-purified antibodies against gamma-tubulin and monoclonal antibodies against acetylated tubulin stain one or two neighboring dots, centrioles. The gamma-tubulin content in two centrioles from the same cell differs insignificantly. Mitotic poles contain fourfold amount of gamma-tubulin as compared with the centrioles in interphase. The effect of nocodazole (5 microg/ml) on interphase cells resulted in lowering the amount of gamma-tubulin in the centrosome, and in 24 h it was reduced by half. Treatment with nocodazole for 2 h caused a fourfold decrease in the gamma-tubulin content in mitotic poles. Besides, the mitotic poles were unevenly stained, the fluorescence intensity in the center was lower than at the periphery. Upon treatment with taxol (10 microg/ml), the gamma-tubulin content in the interphase cell centrosome first decreased, then increased, and in 24 h it doubled as compared with control. In the latter case, bright dots appeared in the cell cytoplasm along the microtubule bundles. However, after 24 h treatment with taxol, the total amount of intracellular gamma-tubulin did not change. Treatment with taxol for 2-4 h halved the gamma-tubulin content in the centrosome as compared with normal mitosis. In some cells, antibodies against gamma-tubulin revealed up to four microtubule convergence foci. Other numerous microtubule convergence foci were not stained. Thus, the existence of at least three gamma-tubulin pools is suggested: (1) constitutive gamma-tubulin permanently associated with centrioles irrespective of the cell cycle stage and of their ability to serve as microtubule organizing centers; (2) gamma-tubulin unstably associated with the centrosome only during mitosis; (3) cytoplasmic gamma-tubulin that can bind to stable microtubules.

Dimerization↗

PubMed1998

Computer-assisted analysis of methylation status of individual interphase nuclei in human cultured cells.

This paper demonstrates that (a) differences in the methylation levels of interphase nuclei can be measured on a cell-by-cell basis, (b) the binding sites of beta-satellite DNA and 5-methylcytosine (5MeC)-rich regions can be localised in interphase nuclei and metaphase chromosomes by sequential in situ hybridization and indirect immunolabelling, and (c) quantitative differences in the relative extensions of beta-satellite DNA and anti-5MeC antibody binding areas can also be measured. This goal was achieved by indirect immunolabelling by anti-5MeC antibodies (Reynaud et al.: Cancer Lett. 61:255-262, 1991) of control and 5-azacytidine-treated human cell cultures. A quantitative analysis of the number, total, and mean areas of labelled heterochromatic regions and the optical densities of euchromatin and heterochromatin was performed for the cells on microscope slides. Dedicated software was used to select and measure the areas of cytological interest. In additional experiments, DAPI-stained slides from control cultures were sequentially treated by in situ hybridization with beta-satellite DNA probe and indirect immunofluorescent labelling with anti-5MeC antibodies. Fluorescent signals of probe and antibodies were pseudocoloured and merged on digital images. The relative locations of probe- and antibody-positive areas were analysed on metaphases and nuclei, and their extensions were quantified in interphase nuclei. Our results show that (a) our analysis can successfully detect different levels of DNA methylation within individual nuclei, (b) in metaphase chromosomes the antibody binding sites are mostly coincident with the hybridisation sites, and (c) in interphase nuclei a quite different picture is consistently observed.

5-Methylcytosine↗

PubMed1993

Comparison between interphase and metaphase cytogenetics in detecting chromosome 7 defects in hematological neoplasias.

Monosomy 7 (-7) is one of the most common chromosomal abnormalities found in the leukemic cells of patients with acute myelogenous leukemia (AML) and myelodysplastic syndrome (MDS). Because patients with -7 have a poor prognosis, their identification is important for treatment planning. Conventionally, -7 is detected by the G-banding technique. This study examines the use of fluorescent in situ hybridization (FISH) methodology to detect -7 cells in interphase nuclei and metaphase chromosomes. Fifteen AML or MDS patients whose leukemic cells were found to have -7 by G-banding at disease presentation were studied. In 13 of these patients, -7 could be detected in interphase by FISH using a chromosome 7-specific centromeric DNA probe. The two patients whose leukemic cells were not detectable by interphase FISH had -7 and t(1q;7p), which were detectable by FISH in metaphase using a chromosome 7-specific painting probe. Metaphase FISH was particularly useful in further defining chromosome 7 defects in cells that contained aberrant or marker chromosomes. For example, in 6 patients, chromosome 7 sequences were detectable in aberrant or marker chromosomes by metaphase FISH, but not by G-banding. These results suggest that metaphase FISH is an important adjunct to conventional cytogenetic methods for defining chromosome 7 abnormalities in AML and MDS patients. Furthermore, interphase FISH is useful for follow-up studies in patients who are found informative for the FISH study at presentation.

Chromosome Aberrations↗

PubMed2006

Evaluation of complete disease remission in acute myeloid leukemia: a prospective study based on cytomorphology, interphase fluorescence in situ hybridization, and immunophenotyping during follow-up in patients with acute myeloid leukemia.

BACKGROUND: Different diagnostic methods add information to define complete remission (CR) in patients with acute myeloid leukemia (AML). The detection of minimal residual disease (MRD) for predicting prognosis and for therapeutic planning still are under discussion. METHODS: The authors studied 216 patients with AML at the time of initial diagnosis and during follow-up and correlated cytomorphology, interphase fluorescence in situ hybridization (FISH), and flow cytometry results to evaluate response status. They further tested the prognostic impact of those results, especially in patients who achieved a morphologic CR. RESULTS: Interphase FISH was found to be correlated significantly with the clinical course at the time of complete cytomorphologic remission and was more reliable than morphology for defining CR. Furthermore, interphase FISH was correlated with immunophenotyping results at all times during follow-up. CONCLUSIONS: The current results indicated that interphase FISH may be used as a valid MRD parameter in patients with AML. Multiparameter immunophenotyping for MRD also was correlated strongly with the clinical course, and the authors suggest integrating such immunophenotyping into the routine diagnostic panel at the time of diagnosis and during the clinical course in patients with AML.

Acute Disease↗

PubMed1986

Removal of cellular water prevents the reformation of the interphase nucleus.

The mature snRNP (small nuclear ribonucleoprotein) particles are localized quantitatively in the interphase nucleus. Like many nuclear antigens, they distribute throughout the cytoplasm after the nuclear envelope breaks down during mitosis and then return to the newly formed daughter nuclei in early G1. Their abundance and stability and the availability of monoclonal antibodies that recognize them, make the snRNP particles a useful model system for studying the reformation of the nucleus at the completion of mitosis. A wide variety of metabolic inhibitors and alterations in normal culture conditions were investigated for their ability to interfere with the return of the snRNP particles to daughter nuclei after mitosis. None of the well-characterized cytoskeletal inhibitors, biosynthetic inhibitors, calcium antagonists, nor ionophores were effective in interfering with this return. However, the removal of cellular water by exposure of cells to hypertonic medium during mitosis blocked the reformation of the nucleus and trapped the snRNP particles in the cytoplasm. In medium of twice the normal tonicity, the function of the mitotic spindle and the cleavage furrow are inhibited, however, the cells reattach to the substratum as if returning to interphase. The chromatin stays condensed and does not form a normal interphase nucleus and the snRNP particles stay dispersed throughout the cytoplasm. This condition is reversible and after return to normal medium the nucleus reforms and the snRNP particles collect in the new nuclei. After gentle extraction of metaphase cells, about 30% of the snRNP particles are soluble, however, the remainder are associated with an insoluble remnant. These data are consistent with the notion that the snRNP particles accumulate in the nucleus due to both preferential solubility and specific binding sites in the interphase nucleus.

Biological Transport, Active↗

PubMed1995

A chromosome 21-specific cosmid cocktail for the detection of chromosome 21 aberrations in interphase nuclei.

Fluorescent in situ hybridization (FISH) with a 21q11-specific probe (CB21c1) consisting of three non-overlapping cosmids has been applied to interphase amniocytes of pregnancies at increased risk for fetal aneuploidy (N = 78) and to interphase lymphocytes, cultured and uncultured, of patients referred for Down syndrome (N = 19 and 28, respectively). In the uncultured amniocytes, six chromosome aberrations were detected: three cases of trisomy 21, a triploidy, a de novo 46,XX,t(21q21q), and a mosaic 46,XY/47,XY,+dic(21)(q11)/48,XY,+dic(21)(q11),+del(21)(q11). In 15 cultured and 20 uncultured blood samples, FISH correctly diagnosed trisomy 21 (full or mosaic) at the interphase level, which was confirmed in all cases by subsequent karyotyping. Because of specific and strong signals in interphase nuclei, CB21c1 appears to be a useful tool for the rapid detection of chromosome 21 abnormalities.

Amniocentesis↗

PubMed2003

Rapid prenatal diagnosis of Down syndrome using quantitative fluorescence in situ hybridization on interphase nuclei.

OBJECTIVES: Presently, conventional cytogenetic analysis of metaphase chromosomes remains the reference approach in prenatal diagnosis. However, this method is labor-intensive and time-consuming. The first step toward the rapid identification of aneuploidies is achieved by interphase fluorescence in situ hybridization (FISH) with centromeric or locus-specific probes. Spot counting using this type of probes is a reliable approach, but is very time-consuming with some technical and biological limitations. In this study, we present a new FISH method using image cytometry for the detection of trisomy 21 within interphase nuclei. METHODS: The method is based on a comparative quantitation of the fluorescence signals emitted by whole chromosome 21 and 22 painting probes cohybridized on interphase nuclei. The chromosomal imbalance was determined with an automated image cytometer by detecting an abnormal ratio of both fluorescence emissions when compared with the ratio obtained in normal cells. RESULTS: Ten blood samples and twenty amniotic fluids were analyzed. Results from FISH and standard cytogenetics were compared and 100% correlation was achieved. CONCLUSIONS: This method, which enables an easy detection of chromosomal imbalances without a need for metaphase preparations, can be applied to the diagnosis of trisomy 21 and extended to other disorders with chromosomal imbalances. Compared to other interphase FISH techniques, it avoids spot-scoring difficulties.

Adult↗

PubMed2001

Role of amniotic fluid interphase fluorescence in situ hybridization (FISH) analysis in patient management.

We retrospectively reviewed 309 amniotic fluid interphase fluorescence in situ hybridization (FISH) analyses performed from October 1995 to June 1999 to assess the role of interphase FISH in the management of patients at increased risk for fetal aneuploidies. Gestational age and indications for amniocentesis, clinical interventions after FISH results, as well as interventions after final culture reports were analyzed. There were 244 (79%) normal, 50 (16%) abnormal and 15 (5%) inconclusive FISH results. There were no false-positive or false-negative results, but there were nine (3%) clinically significant chromosomal abnormalities not detectable by FISH. Of the 50 women with abnormal FISH results, 26 (52%) elected to terminate the pregnancy prior to the availability of the standard chromosome analysis. In two of the fetuses with trisomy 21 no abnormalities were reported by ultrasound examination. Our experience indicates that interphase FISH results played an important role in decision making, especially for pregnancies close to 24 weeks' gestation. Standard karyotype analysis is still required for detection of chromosome abnormalities not detectable by interphase FISH techniques and for clarification of unusual or inconclusive FISH results.

Amniotic Fluid↗