Biomedical subjects
Publications and source records attributed to C L Richer.
A child with trisomy 1q24----qter is described. This syndrome is compared to other 1q partial trisomies. An association is proposed between these trisomic segments and the following phenotypic signs: microphtalmia, trigonocephaly, hypertrichosis, antimongoloid eye slants, anomalies of the biliary tract, and malformations of the central nervous system.
Human late prophase to late metaphase chromosomes were prepared after amethopterin cell synchronization. R-banding was produced by heat denaturation followed by Giemsa staining (RHG). Haploid sets of prophase chromosomes contain approximately 850 bands. Sequences of chromosomes of different degrees of condensation are presented; their analysis provides helpful information to identify the elongated chromosomes and to follow band subdivision. The heat denaturation technique is free from most of the disadvantages encountered with R-banding by 5-bromodeoxyuridine incorporation. Giemsa stained R-bands produced by heat denaturation on prophase and prometaphase chromosomes are useful to analyse the numerous chromosome anomalies involving R-bands. In conjunction with G-banding, it is also important to compare adequately the positive and negative regions of each chromosome to define the anomalies with precision.
The schematic representation of RHG-banded chromosomes (R-banding was produced by heat denaturation followed by Giemsa staining (RHG) in the 850-band range per haploid set, was prepared showing the relative position, the specific size, and the characteristic staining intensity for each band. To this idiogram was adapted the new International Standard Cytogenetic Nomenclature. Our aim was to produce a realistic idiogram which could help in the preparation of R-banded prophase karyotypes and in the localization of chromosomal rearrangements. A comparative analysis of bands at prophase and metaphase revealed certain aspects of the dynamics involved in chromosome condensation and in R-band organization. The effect of chromosome elongation on the appearance of R-bands within heterochromatic regions has also been discussed.
The heterochromatin of the Chinese hamster sex chromosomes was analyzed by different banding techniques. Combined results obtained after differential Ba(OH)2 treatment, BrdU incorporation, Giemsa 11, and staining with quinacrine permitted the characterization of different regions in the heterochromatic portions of the X and Y chromosomes. In the light of these observations, the chiasma observed in the sex bivalent of Chinese hamster spermatocytes was localized within specific heterochromatic regions. The homologous segments consist of the entire short arm of the Y and the distal end of the long arm of the X up to band q21. These regions are probably not rich in highly repetitive DNA sequences, which are more resistant to alkali denaturation, or in satellite DNA, which is stained by Giemsa 11. Thus the heterochromatin in the homologous regions of the sex chromosomes allows the formation of a chiasma. The heterogeneity found in these heterochromatic regions may help to establish a more precise relationship between heterochromatin and recombination.
A family is described in which three normal females transmitted to seven males X-linked mental retardation associated with macro-orchidism and a fragile site on the long arm of the X chromosome -- fra(X)(q27). The affected males also had minor clinical features in common: a large forehead, long face, large ears, a long upper lip and large extremities.
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Cytological studies of peripheral blood lymphocytes from an infertile man revealed the presence of a mosaic trisomy 12. To our knowledge this has not been previously reported in patients. The clinical manifestations in this case enhance the interest of the cytological findings.
Replication times for all important chromosome bands, of both types R and Q (277 structures) are analysed. The R-bands form a group of structures whose DNA replicates during the early S-phase, while the DNA situated in the Q-bands replicates during the late S-phase. There may not exist overlapping between replication times of these two types of structures. The widest R-bands are those which are the earliest to replicate; in general, the most intense Q-bands are those which are the latest to replicate. Especially among these last ones, a certain asynchronism exists between the replication times. Finally the heterochromatin of chromosomes 1, 16 and Y and of the short arms of the acrocentrics could contain two types of DNA which replicate at different times.
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We investigated the endocrine function of a patient with Klinefelter syndrome in which the extra chromosome was an isochromosome Xq. This man was azoospermic but with normal secondary sex characteristics; smallness of the testes was the only abnormal physical finding. High follicle-stimulating hormone (FSH, 70 mIU/mL) and moderately elevated luteinizing hormone (LH, 40 mIU/mL) were found; the FSH and LH response to LH-RH was exaggerated. Androgen and estrogen levels were normal. The insulin test (measure of glycemia, growth hormone, and corticol) and the test with TRH (measure of TSH and prolactin) gave normal results. We conclude that the presence of additional long arms of the X chromosome is sufficient to cause Klinefelter syndrome and that the presence of two extra Xq does not intensify the degree of androgenic insufficiency.
Both dynamic G-banding and cell synchronization produced by bromodeoxyuridine (BrdU), were applied to equine chromosomes. BrdU incorporated during the first half of the S-phase is taken up into the R-bands that are early replicating. These bands, which have incorporated BrdU, cannot contract as usual and remain elongated; only the other regions of the chromosome, i.e., the G-bands, contract normally and are sharply defined. BrdU also can be used for cell synchronization. The addition of BrdU in a high concentration, 15 hours before harvest, and its removal 11 hours later, has two effects: initially the BrdU is incorporated during the first part of the S-phase and then it blocks the cells at mid-S-phase. Within the cell cycle, mid-S-phase appears to be the most vulnerable time to various blocking agents. To differentiate the regions of BrdU incorporation from those that have not been substituted, the fluorescence-photolysis-Giemsa (FPG) technique was applied as modified for horse chromosomes. This dynamic technique, which produces many prometaphase and prophase chromosomes showing very sharp G-bands, is certain to enhance the accuracy of cytogenetic analysis and aid in the standardization of equine chromosomes.
Cell synchronization was used to obtain an adequate percentage of very long chromosomes in equine mitotic spreads. Reported here is our variation, adapted to horse chromosomes, of a method using excess thymidine followed by bromodeoxyuridine incorporation. This technique routinely yields excellent quality cells, predominantly in prometaphase and prophase. Among other differences with the standard technique, this method does not use Colcemid, which, in addition to inhibiting spindle fiber formation, also increases chromosome contraction resulting in thicker and thus fewer bands. Consequently, horse prometaphase chromosomes, which have incorporated BrdU in the late-S-phase, are very long and display a large number of R-bands after the fluorescence-photolysis-Giemsa method. This technique should definitely be useful for the analysis of structural anomalies and the standardization of equine R-bands.