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The staff working in health and medical-social services are a reflection of French society. Many of the employees of these services are migrants, from French overseas departments, whose descendants are particularly high in number in the Île-de-France region. Users of the services, from the 'white' majority group can display racist attitudes., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Analysis of human-rodent hybrids showed the following: the assignment of the ADA1 structural gene to chromosome 20; the identification in hybrids of a new ADA, referred to as ADAx, with a migration more rapidly anodal than ADAd and less rapidly anodal than ADA1 (product of allele 1 or 2); ADAx and d are formed by ADA1 and ADCP (an adenosine deaminase complexing protein). ADCP synthesis is controlled, at least, by a gene (ADCP2) localized on chromosome 2, probably in the IDH1 region; the combined action of another gene (ADCP1), assigned by other authors to chromosome 6, could be neither proved nor disproved, if this gene exists, it must be on 6p or in the 6qter region; the presence of chromosomes 20, 2, and 6 does not constitute a sufficient condition for the formation of ADAx and d, in either the hybrids or the human strains or lines: other factors intervene in its formation, i.e., an interaction between the culture medium, the human parental strain or line, and the rodent parental line.

The value of man-rodent hybrids for detecting creatine kinase BB (CKBB) was greatly increased by the use of an agar technique, in extended incubation (20 hours) with a concentrated solution of creatine as substrate (8 mg/ml instead of 1 mg/ml as usual). The selection of a man-rodent hybrid without discordant between chr. 14 and nucleoside phosphorylase (NP) (a marker of this chromosome) contributed efficiently to the detection of the positive correlation between CKBB and chr. 14/NP. Among 22 independent hybrids, the following were observed : 8 NP + CKBB+, 3 NP + CKBB(+), 11 NP-CKBB- and 6 chr. 14 + CKBB+, 2 chr. 14 + CKBB(+), 11 chr. 14 CKBB-, 2 chr. 14/CKBB+ and 1 chr. 14/CKBB(+). The presence of the chromosome was noted + or - according to its presence in more or less than 30% of the cells. These results show that the gene for CKBB is located on chr. 14 and that the presence of this single chr. 14 is sufficient for the expression of human CKBB in man-rodent hybrids. Discordant results reported by others (Povey et al., 1979) may be due to the weakness of the human CKBB detection in man-rodent hybrids or to the bad conservation of this enzyme.

Analysis of different human tissues showed that glutathione S-transferase (GST) of fibroblasts and leucocytes is GST3, an enzyme found in liver extracts by Board (1981). Consequently, the GST localized on human chromosome 11 by Silberstein and Shows (1981, 1982) is GST3. Analysis of tissue extracts showed a new GST band, very intense in muscle extracts and very weak or absent in other tissues, and called GSTM. Analysis of man-rodent hydrids showed synteny between LDHA, GST3, ESA4 and localization of this synteny group on chromosome 11. Analysis of discordant percentages and discordant types between markers favored the following assignments: LDHA on 11p12, GST3 on 11q13 leads to 11qter, ESA on 11q13 leads to 11q22. The present study suggests assignment of GST3 to 11q13 leads to 11q22. Different types of man-rodent hybrids are useful for human gene mapping. A new type hybrid, as used here (nonadhering to glass or plastic surfaces), appears useful because of rapid proliferation and growth in suspension, the latter feature facilitating culture and harvesting.