Sensitivity of follicular melanoblasts in newborn mouse skin to tritiated thymidine: Evidence for a long term retention of label

Summary Injection of tritiated thymidine into newborn mice results in a progressive greying of hair that does not begin until after the first hair coat is grown. After a year the depigmentation is appreciable (about 60% of the hair are white). The effect cannot be simulated by external irradiation of newborn mice or by the administration of radioactive uridine or methionine. The effect can best be explained by a long-term retention of radioactivity in the DNA of melanocyte stem cells (melanoblasts) in spite of several rounds of cell division. This could be achieved by labelling the strands of DNA destined to act as templates throughout life by being selectively retained in the stem line as described in Cairns' hypothesis.Acknowledgments. This work was supported by grants from the Cancer Research Campaign. I am indebted to Joan Bullock for her careful, patient help with these experiments. CSP is a fellow of the Cancer Research Campaign.     

In vitro studies on the biosynthesis of a glycoprotein associated with normal and tumoural growth in the rat

Résumé La biosynthèse d'une glycoprotéine, isolée à partir d'une tumeur induite au 2-amino-acetylfluorène, a été étudiée in vitro, par la culture de la moëlle osseuse du rat, du poumon et du foie embryonnaire. Cette étude a été faite à l'aide d'acides aminés radioactifs dans le milieu et, subséquemment, par radio-immunoélectrophorèse. Le dosage quantitatif de la biosynthèse in vitro, par les tissus, a été fait par la méthode électrophorétique d'agarose contenant un anticorps monospécifique préparé chez la chèvre, contre la glycoprotéine pure. La spécificité de la méthode a été éprouvée en utilisant, comme contróle, l'incubation des tissus morts et en ajoutant de la puromycine dans le milieu.

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Investigation supported by the National Cancer Institute of Canada and by the Medical Research Council of Canada     

Loss of virulence of canine distemper virus is associated with a structural change recognized by a monoclonal antibody.

The monoclonal antibody (mAB) L1, which binds to the nucleocapsid protein of canine distemper virus (CDV), was shown to bind to avirulent CDV obtained after serial passages in Vero cells, but not to two different virulent demyelinating CDV-strains propagated in dog glial cell cultures. However, when both virulent CDV-strains were passaged through Vero cells they expressed, after a number of passages, an epitope recognized by mAB L1. The occurrence of the L1 epitope appeared to coincide with loss of virulence in animal inoculation experiments.     

Stimulation of proliferation of rat spleen cells, in vitro, by a nonspecific acute inflammatory exudate. Modulation of cell response to phytohemagglutinin (PHA)]

The effect of an acute non-specific inflammatory exudate with mitogenic activity on macrophages in culture has been tested on the spontaneous and PHA-induced DNA synthesis of spleen cells in vitro. Stimulatory effect of this exudate was observed on spontaneous DNA synthesis which was detectable over a range of 1 : 4 to 1 : 4,000 concentrations. After optimal PHA stimulation, an inhibition of mitogen-induced DNA synthesis was observed when the cells were exposed to the highest concentrations (up to 1 : 128) of the exudate. Thereafter, the phenomenon could be reversed and the stimulation was maximal at a concentration of 1 : 2,000. When a sub-optimal dose of PHA was used, the simulatory effect was more pronounced and detected from 1 : 8 up to 1 : 4,000 concentrations.     

Inhibition of ovulation in rats by antagonists to serotonin and by a new tricyclic compound.

The ovulation inhibiting activity in adult rats of the 5HT-antagonists cyproheptadine, mianserin and methysergide is shown. Furthermore the activity of a newly synthetized Cycloheptathiophenederivative, compound 26-921, which inhibits LH-secretion and consequently ovulation, is described.     

Double infection in a mosquitoArmigeres subalbatus (Coquillett) (A. obturbans auct.) with two different species of filaria

Résumé Étude de l'infection simultanée du moustiqueArmigeres subalbatus par deux espèces de filaires,Brugia pahangi etBreinlia sergenti. Les stades de developpement de ces filaires peuvent être facilement differenciés du fait que leB. pahangi se tient exclusivement dans la musculature thoracique et leB. sergenti dans le tissu adipeux.     

Permanent cell culture of a pancreatic carcinoma induced by immunological effect. Comparison of the evolution of secretory specificity and oncogenic power in two homologous strains: in vitro (147-8) and in vivo (7-4)]

A permanent epithelial cell strain, named 147-8, was established in vitro from a pancreatic carcinoma immunologically induced in a mouse. The cells remain isolated and grow actively in suspension: after more than 3 years of life, the doubling time is 14 hrs. Some cells synthetized insulin during the first two months. Later on, the cells contain low but significant levels of amylase and lipase, even during the second year, thus showing some pancreatic specificity. The oncogenic property of this strain is high during the first two years, and later decreases while their multiplication rate remains high. The evolution of 147-8 strain is compared to that of its in vivo homologous strain 7-4.     

HLA phenotypes in patients surviving a long time after immunotherapy with BCG for acute childhood lymphoblastic leukemia. Arguments in favor of the existance of a gene for immune response in human leukemia]

HLA phenotypes of 13 patients surviving in lasting first remission over 6 years after BCG immunotherapy for acute childhood lymphoblastic leukaemia (ALL) were compared to phenotypes of normal subjects and of surviving ALL patients treated exclusively with chemotherapy. Among the BCG-treated patients, the frequency of the antigen HLA-BW 17 was 46.1% vs 7.3% in healthy controls (p less than 0.001) and the frequency of the antigen HLA-AW 33 was 30.8% vs 1.2% (p less than 0.001). 9 patients possessed at least one of these two antigens (69.2% vs 8% in controls p less than 0.001). Phenotypes of the chemotherapy-treated patients did not differ significantly from controls. These results suggest the existence in humans of HLA-linked genes which are involved in the response to BCG immunotherapy in ALL.     

Enzymatic test for the detection of a riboflavin deficiency. NADPH-dependent glutathione reductase of red blood cells and its activation by FAD in vitro

Zusammenfassung Die NADPH-spezifische Glutathion-reduktaseaktivität hämolysierter Erythrozyten erscheint brauchbar als Parameter zur Erfassung von Riboflavin-mangelzuständen. Die Enzymaktivität wird in vitro durch einen Zusatz von FAD bei Riboflavinmangelratten wesentlich stärker erhöht als bei Kontrollratten. Untersuchungen mit menschlichen Erythrozyten deuten darauf hin, dass auch hier die Aktivierbarkeit des Enzyms durch FAD vom Riboflavinstatus abhängt.

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The following abbreviations are used: NADPH, reduced form of nicotinamide adenine dinucleotide phosphate (triphosphopyridine nucleotide); FAD, flavin adenine dinucleotide.     

Extra-nuclear inheritance in a sexually produced aphid: the ability to overcome host plant resistance by biotype hybrids of the greenbug,Schizaphis graminum

Summary Greenbugs of biotype E that grow and reproduce well on a biotype C-resistant sorghum (IS 809) were crossed with biotype C greenbugs. The resulting hybrids were tested on IS 809 to study how the ability to overcome the cultivar's resistance is inherited. Only those hybrids stemming from biotype E mothers were able to overcome the resistance of IS 809 plants, indicating that this trait is inherited by the sexually-produced fundatrices in an extra-nuclear manner from the mother. A plausible explanation for this phenomenon is presented.