Plasmid-phage recombination in T7 infected Escherichia coli

Recombination between genetically marked T7 bacteriophage and plasmids containing inserts of T7 DNA has been studied in order to gain some insight into the phage recombination process. The results suggest that plasmid-phage recombination requires the products of T7 genes 3 (endonuclease), 4 (DNA primase), 5 (DNA polymerase), and 6 (exonuclease), as has been demonstrated previously for phage-phage recombination. Plasmid replication does not compensate for a complete block in phage polymerase synthesis, suggesting a direct role for this enzyme in recombination, rather than an indirect role, by means of producing replicative structures that are recombinogenic. In most respects, plasmid-phage recombination appears to be similar to phage-phage recombination. The participation of two autonomous, structurally dissimilar, homologues, however, might render certain aspects of the recombination process more amenable to analysis. As examples, the characterization of an apparent marker effect and the demonstration of genetic heterozygotes among the products of plasmid-phage recombination are presented.     

Half-body irradiation for pain relief

Half-body irradiation (H.B.I.) is a relatively recent technique in the palliative and analgesic treatment of advanced disease. At Tenon Hospital 21 patients (17 males and 4 females) were treated with this technique (2 upper and lower half-body irradiation, 7 upper half-body irradiation and 12 lower half-body irradiation). The mid-plan dose was 8 grays in one fraction, limited to 6 grays at the level of the lungs. The pain relief effect was excellent in ten cases and very good in eight cases. The effect was prompt (before 48 hr) and long lasting. General tolerance was excellent without any pulmonary complication. The hematologic tolerance was good even in the patients previously treated by combined chemotherapy. This irradiation seems to be a major weapon as an antalgic treatment of the advanced solid tumours. It can be proposed as a treatment which will enable tumour reduction in the future.