Biomedical subjects
Publications and source records attributed to P Jalbert.
Cytogenetic studies were performed at the time of diagnosis on two patients with diffuse small cell lymphocytic lymphoma. Both patients had a similar simple karyotype with a t(13;17)(q12-14;p12-13). These observations confirm the nonrandom involvement of band 13q13 in chronic lymphoproliferative diseases.
The karyotype of 443 infertile males has been studied (infertility of unknown etiology). The sample has been divided in 3 groups according to the data of their spermogram: Gr 1--101 males with a normal spermogramm (selected through the sterility of their couple). Gr 2--185 infertile males with oligospermy (less than 20 millions spermatozoal/ml). Gr 3--157 infertile males with azoospermia. This study shows: --No significant difference in chromosomal aberration rate between group 1 and general male population. --A rate of 5% chromosomal aberration in group 2 (versus 0.7% in normal male population p less than or equal to 10(-8], nearly exclusively balanced translocations. --A rate of 21% chromosomal aberration in group 3, nearly exclusively 47, XXY or 46, XX (p less than or equal to -9). The karyotype is unlikely to bring any information in infertile males with normal spermogram; on the contrary it is of valuable interest in infertile males with abnormal sperm.
71 samples taken by the transabdominal route were compared with 71 samples taken by forceps through the cervix. A fine (1 mm) transabdominal choriocentesis needle with a thin wall (0.1 mm), a short bevel, and a lateral hole was made to bring together simplicity, effectiveness and safety; success was obtained in 95% of the cases (39/41) of our last 41 samples on the first attempt. For comparison with the forceps, the success rate on the first attempt was only 66% (26/41), but it rose to 97.5% if the patient could take 3 attempts at most. The forceps made it possible to collect a mean quantity large enough (19.9 mg) but it was quite variable (16.7 mg being the range) of complete villi, whereas the choriocentesis needle only gathered a smaller volume (12.7 mg) but more reliable (the range being 3.7 mg). The villi were fragmented, however. To work out the study of the DNA and the karyotype, there is a choice between the forceps and the needle. This choice depends principally on the damage the two techniques can do. This has not been worked out yet in our study except indirectly.
Using the technique of in vitro human-hamster fertilization, sperm of four men heterozygous for 4 reciprocal translocations--t(4;17),t(5;13),t(6;7), and t(9;18)--was studied. Frequencies of numerical abnormalities unrelated to the translocations range from 8.3% to 13.3%, and the incidence of imbalances ranges from 23.0% to 66.0%. Results are pooled with data from the nine other reciprocal translocations reported elsewhere, and the combined data demonstrate that male meiotic segregation is not random: whatever the type of translocation may be, the distribution of imbalances in sperm is constant, with approximately 72.0% adjacent 1, 18.5% adjacent 2, and 9.5% 3:1 segregations. The same prevalence of adjacent 1 segregations as that reported at term for translocations of paternal origin is observed. There is a strong postzygotic elimination process; for a given translocation it affects selectively the maximum-imbalance zygotes so that imbalanced segregations observed at term are always predetermined.
Sperm cytogenetics was carried out using technique of in vitro heterospecific human-hamster fertilization. Sperm of 4 men heterozygous from 4 reciprocal translocations (t(4; 17), t(5; 13), t(6; 7) and t(9; 18] was studied. Segregations were various but a majority of unbalanced complements resulting from adjacent 1 segregations was observed. This prevalence was stronger when the pachytene diagram predisposed the translocation to this mode of imbalance at term.
Segregation modes of human reciprocal translocations are briefly described. Risk figures and mode of imbalance at term differ greatly from one translocation to another. The causes of these variations are analysed and a genetic counselling proposed for each case.
Artificial reproductions using donor sperms or oocytes are increasing. In this way they offer the doctor the chance of preventing genetic handicaps that cannot be obtained by natural reproduction, and that therefore should be used. To deny this medical power is dangerously nihilistic. The use of this power for eugenic or commercial ends can lead to abuses. Therefore a strict medical protocol is proposed: 1) The use should be exclusively therapeutic and should include the genetic reasons for using a donor gamete in reproduction. 2) The objectives should be defined and the methods that can be employed in the prevention of abnormal genetic inheritance. 3) Research should be carried out into the possible iatrogenic effects of these methods of artificial reproduction.
Artificial insemination with donors has genetic repercussions which increase with its impact on demography. Genetic control of semen donors offers a possibility of preventing the main genetic handicaps. The French Federation of Human Semen Study and Preservation Centres (CECOS) is currently organizing such a control system. The reasons for this and the modalities of the system are given in this article.
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From 7 cases of abnormalities involving chromosome 13, the structural gene(s) coding for coagulation factors VII and X were located in the region 13q34-13qter. Gene-dosage effects for these coagulation factors seem to act in both directions, causing a decrease when there is monosomy of segment 13q34, but also, as has not been demonstrated before, an increase when there is trisomy of this same segment.
A cytogenetic analysis of seventy human sperms originating from seven normal subjects is described. Results are compared to those of previously reported studies. The share of male and female contributions in the genesis of chromosomal abnormalities in human zygotes is discussed.
The incidence of chromosomal abnormalities at conception has been estimated to be very high about 40%; these estimations have been made on indirect evidence provided by karyotyping spontaneous abortions products. Now direct evidence is available, consisting in sperm chromosome analysis by using fertilization of zona-free eggs of the golden hamster. In our experience 175 assays have been performed with modifications of the technique described by Martin et al. (1982) and by Brandriff et al. (1984). Consistent results are obtained since the last 30 assays, using for the first time an R banding technique. Chromosomal analysis of 48 spermatozoa from 7 normal males is reported. The frequency of abnormal sperm complements (21%) is higher than reported by previous reports.
A significant decrease of sister chromatid exchange (SCE) frequencies was observed in Bloom's syndrome(BS) fibroblasts by cocultivation with normal fibroblasts at 5:1, 1:1, 1:5 ratios, and by culture in medium previously used to support normal fibroblasts. On the other hand, the SCE rate of normal fibroblasts was not modified. These results are compared with those from other studies and discussed.
One of the children of a t(15;22) (q111;p11) woman has lost the minute metacentric der(15) without any clinical consequence, indicating the inocuity of the 15pter----q111 and 22pter----p11 monosomies. The segregation mechanism of this monosomy and, from this family, the relation between reciprocal translocations and Robertsonian translocations are discussed. Another subject with r(22) in the same family questions on an hypothetic common origin.
Cytogenetic study of a case of Bloom's syndrome (number 46 of the international registry) confirms the excess of exchanges in all cellular types with the exception of a minority of lymphocytes and of two lymphoblastoid cell lines. These exchanges are produced in an X or U fashion between sister chromatids or between homologous chromatids and produce both simple and complex figures for which symmetry is the common feature. Some of these structures are rearranged secondarily, producing centric or acentric fragments and marker chromosomes. Triradial configurations are considered to be the result of exchanges rather than of partial endoreduplication. Chromatid and chromosome breaks are interpreted to result from incomplete exchanges. It is suggested that the general propensity for exchanges is the primary event responsible directly or indirectly for the cytogenetic observations rather than a defect in one of the DNA-repair mechanisms. No increase in mitomycin C sensitivity appears in vitro. The excess of SCEs is partially correlated by contact in vitro with normal cells and to a lesser degree by the culture medium in which the cells were grown.
Hypothesis on the nature of the fragile site Xq28 and its relations with the specific phenotype are discussed. The roles of a local inactivation (tested by G6-PD activity in 9 patients) or of a deletion Xq28 leads to qter (studied by morphometric evaluations on 2 patients and their heterozygotic mother) are not confirmed.
Structural chromosome anomalies (1 477 cells examined) and sister chromatid exchanges after two replication cycles with BrdU (771 cells studied) were evaluated in 12 patients with diffuse scleroderma and having received no recent or important irradiation. The increase of structural anomalies, chromatidic as well as chromosomal, is always low, inconstant and cannot be considered as having a diagnostic value. Increase of sister chromatid exchanges could be a more sensitive method of investigation. In particular, it is not influenced by low doses of diagnostic X-rays.
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