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Micronucleus test and bone-marrow chromosome analysis: a comparison of 2 methods in vivo for evaluating chemically induced chromosomal alterations.

The sensitivities of 2 cytogenetic tests, chromosome analysis and the micronucleus test, were compared by using mice exposed to the substances methyl methanesulfonate (MMS), mitomycin C (MC) and procarbazine (Natulan). The lowest dose at which a significant effect could be observed in bone-marrow cells of mice was determined. Both test systems proved equally sensitive for MC and procarbazine. Doses as low as 0.16 mg of MC per kg and 3.12 mg of Natulan per kg significantly increased both the aberration rates and the micronucleus rates above those of the controls. In contrast, after exposure to MMS, chromosomal aberrations were elevated above control levels at 5 mg/kg, and the micronucleus rate differed significantly from that of the controls after a dose of 10 mg/kg. With the present protocol and sample size one can conclude that the micronucleus test is generally comparable in sensitivity to the chromosome analysis. However, the MMS data indicate that there might be chemicals for which the resolution of the chromosome analysis is higher. When the mutagens were given in 2 single i.p. injections separated by 24 h, the polychromatic erythrocytes were analyzed for the presence of micronuclei 6 or 24 h after the second injection. The double treatment did not increase the micronucleus rates above the single-treatment results at either sampling interval.

Animals↗

Current techniques in chromosome analysis.

New techniques in chromosome analysis provide more precision in the identification of chromosomal abnormalities than was previously possible. Specific small chromosome changes can now often be related to defined syndromes of mental retardation and congenital anomalies, or to malignant disease. Some aspects of chromosomal function can also be investigated cytologically, e.g., abnormalities in DNA repair, susceptibility to damaging agents, DNA replication sequences, and sites of inactive heterochromatin and of actively transcribing ribosomal DNA. Future trends will involve even finer resolution of the chromosomal bands, using both extended chromosomes and probes specific for small chromosomal regions, as well as continued localization of specific genes on the cytologic map.

Bromodeoxyuridine↗

Application of scanning force microscopy to chromosome analysis.

The application of scanning force microscopy (SFM) to the imaging and analysis of chromosomes is described. This relatively new microscopical technique has been used to provide high-resolution, three-dimensional images of uncoated and unstained human chromosomes in which surface features less than 50 nm have been resolved. Comparison of SFM images with light microscopy data has permitted identification of specific chromosomes, and images of a chromosome showing a cytogenetic abnormality are presented. These preliminary results demonstrate that this technique has potential applications in the imaging and analysis of chromosome structure.

Chromosomes, Human↗

Porcine APP cDNAs: molecular cloning and characterization, expression analysis, chromosomal localization and SNP analysis.

The human amyloid precursor protein (APP) is the precursor of Abeta, a peptide with the potential to create amyloid plaques in neurons. Mutations in the human APP gene are associated with the familial form of Alzheimer's disease. In addition, differential expression of three alternative pre-mRNA APP splicing variants of 695, 751, and 770 amino acids is linked to the pathogenesis. In this study, two novel transcript variants of porcine APP have been identified, producing isoforms of 695 and 751 amino acids, respectively. These are highly homologous to APP orthologues from other vertebrate species. Expression analyses revealed that the gene is expressed in all 30 examined porcine tissues and in a selected subset of these, differential representation of the three major APP transcript variants was observed. The APP isoform of 770 amino acids clearly predominates in non-neuronal tissues while in porcine cerebellum, the APP isoforms of 695 and 770 amino acids are expressed at equivalent levels. Employing a somatic cell hybrid panel, the APP gene was mapped to porcine chromosome 13 in either the 13q41 or 13q46-q49 region. A large pig population was screened for single nucleotide polymorphisms (SNPs) in APP exon 17 and flanking intron sequences. No missense mutations were detected; however, the allele frequencies of two silent mutations and two intron polymorphisms varied significantly among breeds.

Amino Acid Sequence↗

Detection of chromosome aberrations in twelve primary gastric cancers by direct chromosome analysis and FISH.

Direct chromosome analysis and FISH were performed on twelve primary gastric carcinomas. Two of them had simple chromosome changes: 48, XX, +8, +20, and 49, XY, +2, +8, +9, and the others had complicated chromosome changes, which includes much more numerical and structural chromosome aberrations. Frequent structural changes in the complicated types involved chromosome 7, 3, 1, 5 and 12 etc. The del 7q was noted in eight cases. The del (3p) and del (1p) were noted in six and five cases, respectively. The results provide some important clues for isolation of the genes related to gastric cancer.

Adenocarcinoma↗

Direct chromosome analysis from neonatal cord blood.

Direct chromosome preparations of neonatal cord blood provides the unique opportunity for rapid chromosome analysis (turnaround time; 6 hr), without the necessity of bone marrow aspiration. Based on 42 samples we confirm the finding of Garnham and Sutherland [1987] for suitability of cord blood for direct chromosome preparation. Procedural modifications are provided for higher yield of cells for chromosome analysis. The procedure may well be of major significance for rapid diagnosis of neonates who suffer from aneusomy.

Azure Stains↗

Packed red cell transfusion does not compromise chromosome analysis in newborns.

PURPOSE: Critically ill neonates are frequently transfused with packed red cells. Some of these transfused neonates also need chromosome analysis. There is a long-standing tradition in pediatrics of not performing chromosome analysis after transfusion. We wished to determine whether transfusion with packed red cells affect the cytogenetic results in neonates. METHOD: The medical records of all neonates at the Medical College of Georgia who had had chromosome analysis between June 1995 and June 1998 were reviewed. Ten neonates had received transfusion prior to cytogenetic testing. Of these 10 infants, two had been transfused two or more times. Routine cytogenetic analysis of 20 metaphases at 550-band level had been performed on all 10 patients. Heteromorphic markers were compared in 10 randomly selected metaphases for any discrepancy. To determine whether there were theoretical reasons to delay chromosome analysis in transfused neonates, samples of irradiated, and/or filtered, and nonfiltered blood were obtained from the blood bank and analyzed for the presence of lymphocytes. RESULTS: Prior transfusion did not affect karyotype results. A nonmosaic abnormal karyotype was found in 3 of the 10 patients. A fourth patient's karyotype was 45,X/47,XXX. This mosaicism was constitutive and consistent as demonstrated by a follow-up chromosome analysis. All other abnormal karyotypes were consistent with the dysmorphic phenotype. Randomly selected metaphases did not show any differences in the identifiable heteromorphic markers in all 10 patients. Although there was a 50% chance of patients receiving blood from a donor of opposite sex, there were no instances in which cells with a karyotype of the opposite sex were found in the patients' blood. The irradiated and filtered cultured donor blood samples did not show any metaphases. However, metaphases were seen in the cultures from nonfiltered and nonirradiated donor blood. CONCLUSIONS: Based on these results one does not need to delay karyotyping babies who have had blood transfusions. Packed red cell transfusion in newborns does not compromise the accuracy of chromosome analysis in our study even with multiple transfusions.

Chromosome Aberrations↗

Reproductive outcome after chromosome analysis in couples with two or more miscarriages: index [corrected]-control study.

OBJECTIVE: To compare reproductive outcomes in couples carrying a structural chromosome abnormality and non-carrier couples referred for chromosome analysis after two or more miscarriages. DESIGN: Index [corrected]-control study. SETTING: Six centres for clinical genetics in the Netherlands. PARTICIPANTS: 278 carrier couples and 427 non-carrier couples referred for chromosome analysis between 1992 and 2000 after two or more miscarriages before 20 weeks of gestation. Couples were followed up for at least 24 months after chromosome analysis. MAIN OUTCOME MEASURES: The birth of at least one healthy child, at least one more miscarriage, and viable offspring with unbalanced chromosomal abnormalities after parental chromosome analysis. RESULTS: Mean follow-up after chromosome analysis was 5.8 years. 120 of 247 (49%) carrier couples had one or more miscarriage after chromosome analysis compared with 122 of 409 (30%) non-carrier couples (difference 19%, 95% confidence interval 11% to 26%; P < 0.01). The percentage of couples with at least one healthy child was not significantly different in carrier couples (83%) and non-carrier couples (84%) (difference -1%, - 7% to 5%). Among 550 pregnancies in carrier couples, two viable unbalanced chromosome abnormalities were detected at prenatal diagnosis (0.4%) and the fetuses aborted and two children with an unbalanced karyotype were born (0.4%). CONCLUSIONS: Couples whose carrier status was ascertained after two or more miscarriages have a low risk of viable offspring with unbalanced chromosomal abnormalities. Their chances of having a healthy child are as high as non-carrier couples, despite a higher risk of miscarriage.

Abortion, Habitual↗

Chromosome analysis before birth and its value in genetic counselling.

Chromosome analysis of amniotic cell cultures was achieved in 29 out of 30 consecutive patients who were referred for genetic counselling during pregnancy. Amniocentesis was performed without any apparent untoward maternal or fetal complication. The only pregnancy terminated was that of a carrier of X-linked granulomatous disease, in whom the amniotic cells showed that the fetus was male and also had Down's syndrome (trisomy G). Chromosome analysis in the remaining 28 patients showed normal karyotypes. The interval between amniocentesis and a definitive karyotype varied from 7 to 31 (average 18.4) days.The reliability of chromosome analysis from amniotic cell culture and of fetal sex determination by means of the sex chromatin and Y-fluorescence techniques was studied further in amniotic fluid from cases of therapeutic abortion and of rhesus incompatibility. The fetal sex was correctly determined in all cases. It is concluded that antenatal diagnosis of genetic disease by amniocentesis now permits a more practical approach to genetic counselling.

Abortion, Induced↗

Chromosome analysis and cell cytology in effusions. A comparative study.

Chromosome analysis and conventional cytology have been done on serous effusions from 35 patients, 21 of whom had a final clinical diagnosis of malignant disease and 14 of non-malignant disease. Sixteen of the malignant cases were previously untreated. Cytology disclosed nine cases as malignant, three as suspect malignant and nine as normal. The comparable figures for chromosome analysis were 14 malignant, two suspect malignant, and five normal. Neither of the methods gave false positive results in the small series of non-malignant disease. In the present study chromosome analysis has thus provided greater diagnostic accuracy than cytology on serous effusions of malignant disorders.

Aged↗

Automatic chromosome analysis. II. Karyotyping of banded human chromosomes using band transition sequences.

Human chromosomes, represented by band transition sequences, chromosome area, centromeric index by area and centromeric index by density, were karyotyped by computer. A reference set of chromosomes provided frequencies of occurrence of each density class and difference class of the band transition sequence as well as of each of the three global features. The karyotyping program was designed to handle all metaphases, even those from which severely bent and overlapped chromosomes were excluded. In one experiment, 21 metaphases were karyotyped on the basis of a reference set and the results were compared with earlier results of visual analysis of band transition profiles developed from band transition sequences: 0.8% errors were made in the visual experiment and 1.4% errors were made in the computer based experiment. In a second experiment, 179 metaphases were divided into reference and test sets and karyotyped by computer with an error rate of 3.4%. By further analysis it was found that metaphases with many misclassified chromosomes could often be automatically distinguished from metaphases with few errors. Thus by automatic rejection of 7% of the metaphases the error rate could be reduced to 2.6%. The computer program for chromosome karyotyping will now be implemented in a semi-automatic system for practical clinical chromosome analysis.

Chromosome Banding↗

Chromosome analysis guidelines preliminary report.

These guidelines have been developed by the Association of Cytogenetic Technologists (ACT) for chromosome analysis. In formulating its recommendations, the task force reviewed guidelines established by several states and regional genetics groups. Draft guidelines prepared by the task force were reviewed by a panel of expert consultants, all of whom are laboratory directors and well known in their respective fields of expertise. The intention of the task force was to reflect procedures that are believed to be generally accepted by cytogenetic laboratories as basic criteria for effective chromosome analysis and that are consistent with existing cytogenetic quality assurance guidelines. It is important to stress that the primary purpose of the task force at this time is to establish guidelines for chromosome analysis. While the present guidelines address issues other than chromosome analysis, they do so incidentally and only in general terms. A more comprehensive discussion of other technical aspects of cytogenetics can be found in the forthcoming second edition of the ACT Cytogenetics Laboratory Manual. It is important to note that these guidelines are not intended to prescribe appropriate analyses for all individual circumstances. That determination is appropriately a matter for the judgment of the laboratories concerned. ACT, its members, and the task force that assisted in preparation of these guidelines make no warranty and assume no liability with respect to the information contained herein.

Amniotic Fluid↗

Chromosomal analysis of colonic adenomatous polyps.

Chromosomal analysis of 25 colonic adenomatous polyps was performed by a direct method similar to that used in prenatal diagnosis of chromosomal aberration on chorionic villi. Fourteen lesions showed an abnormal karyotype. Two changes were recurrent: trisomy 7 (observed in eight cases) and trisomy 13 (observed in seven cases). No monosomy of the short arm of chromosome 17 was observed even at the level of two polyps with in situ carcinoma lesions.

Adenocarcinoma↗

Should the indications for prenatal chromosome analysis be changed?

Amniocentesis for chromosome analysis was performed in 1086 pergnant women, 739 of whom had an increased risk of giving birth to a child with chromosome abnormalities. Such abnormalities were found in almost identical proportions among the fetuses with an increased risk (1.2%) and among those with no increased risk (1.4%). Findings in several other studies seem to confirm that there is no significant difference between the risk groups in the proportion of abnormalities found. This suggests that our current risk groups may not be the right ones, but a much larger study is needed to confirm this.

Amniocentesis↗

Chromosome analysis in patients with sarcoidosis.

Chromosome analysis of lymphocytes from the peripheral blood of 20 patients with sarcoidosis and 10 healthy controls showed a significantly greater number of hypomodal cells among the patients. Two patients receiving systemic treatment with glucocorticoids had many chromosomal aberrations.

Adult↗

A comparison between flow cytometric ploidy investigation and chromosome analysis of 32 human colorectal tumors.

The correlation between flow cytometric ploidy investigation and classic chromosome analysis was studied in 32 human colorectal tumors. Flow cytometry was performed by nuclei isolation and DNA staining with ethidium bromide. Chromosome analysis was done after incubation with colcemid. In 12 cases, chromosome identification was possible by grouping according to the Denver system or by Q-banding. Generally, the measured DNA content corresponded well with the content expected from chromosome analysis, giving an average difference of 4%. In nine tumors, the measured DNA content was 4-18% higher than expected. Some of these discrepancies could be due to difficulties in identifying the corresponding cell populations in heterogeneous tumors. However, in general the number of cell populations and their quantitative representation by the two methods were statistically well correlated. The results indicate that flow cytometric ploidy investigation of colorectal tumors with the present technique is a reliable method, but also that a combination of both techniques may yield additional information about tumor cytogenetics.

Colonic Neoplasms↗

Chromosome analysis of 894 patients.

Metaphase chromosome analysis from cultured blood lymphocytes was performed in 894 consecutive patients from the year 1981 to early 1989. G-bands by trypsin using Giemsa (GTG) was routinely employed during the last five years supplemented with other banding techniques if required. High resolution chromosome banding was performed in cases suspected of structural chromosome abnormality. Successful studies were obtained in 862 (96.4%). Out of the successful cases, 232 (26.9%) had informative results, and 193 (22.4%) had chromosome abnormalities. Down's syndrome was found in 110 cases. Edwards' and Patau's syndromes were found in 4 and 7 cases respectively. A case of trisomy 14 mosaic was found. There were 2 cases of trisomy 22 syndrome, one case with 46,XX/47,XX,+mar(22) and another case with 46,XX/47,XX,+r(22) karyotype. There were 39 cases of sex chromosome abnormalities, 27 of which had Turner's syndrome. Kline-felter syndrome was found in 8 patients. Triple X syndrome and true hermaphrodite (46,XX/46,XY) was each found in one case. Autosomal deletions were found in 19 patients. Autosomal duplications were found in 4 patients, and autosomal translocations were found in 10 patients. Some of these autosomal structural abnormal cases have been included in the chromosomal syndromes mentioned above.

Adolescent↗

Chromosomal analysis of sixteen human rhabdomyosarcomas.

Chromosomal analysis of 16 rhabdomyosarcomas was done from four primary tumors and from 12 tumors after nude mouse passage. Seven tumors were alveolar; four of these had t(2;13)(q37;q14) and in two tumors it was the only structural abnormality. The other three alveolar tumors were near tetraploid with marker chromosomes and double minutes. In the nine embryonal tumors studied, one had a normal karyotype, and eight were abnormal. Although the eight tumors had no common structural abnormality, trisomy 2 was present in all.

Animals↗