Volume feedback and generalization techniques in shaping speech of an electively mute boy: a case study

An “electively mute” 12-yr.-old boy was successfully treated using positive reinforcement procedures. Visual feedback from the volume-level meter of a tape recorder was used to help in inducing sounds and to aid in raising speech volume. Various other techniques were employed to increase the rate of speech and to generalize it to a variety of environmental situations.

Influence of the diet on the turnover of bile acids in germ-free and conventional rats

1. [24-14C]cholic acid was given to conventional and germ-free rats and the faecal isotope excretion studied for 8 days. The turnover, pool size and daily excretion of cholic acid and its metabolites were calculated for rats on three different diets, i.e. a commercial type diet (pellets), a semi-synthetic diet without (D7) and with 20% cellulose (D7+cellulose). The transit time of the intestinal contents was evaluated by following the excretion of an orally administered dose of carmine.

2. The amount of bile acids excreted was two to three times higher in both conventional and germ-free rats receiving pellets than in those receiving diet D7. This difference in bile acid excretion between animals receiving different diets cannot, therefore, be caused by an influence of the diet on the gastro-intestinal microflora. This effect of the commercial diet could not be due to a high fibre content, since an increase in the fibre content of the semi-synthetic diet D7 by the addition of 20% cellulose did not reproduce the effect obtained with the commercial diet.

3. The difference observed in bile acid excretion between germ-free and conventional rats on diet D7 was mainly ascribed to the much longer transit time of intestinal contents in germ-free as compared with conventional rats.

Unscheduled incorporation of thymidine in ultraviolet-irradiated human lymphocytes

The nature, degree, and kinetics of unscheduled thymidine incorporation previously shown to occur in 90 % of irradiated lymphocytes was stud-incorporation was sever ely depressed i n t h e presence of 10(-4) M acriflavine and by low temperature, but was unaffected by 10(-3) M hydroxyurea or caffeine. Over a dose range of 25 to 400 ergs/mm2, the uptake of thymidine was increased by a factor of only 1.6, although the survival of lymphocytes, measured 5 days after irradiation, decreased by almost two orders of magnitude. (The survival curve suggests that 90% of the lymphocytes have a D0 of 35 ergs/mm(2) and 10 % have a D0 of 250 ergs/mm(2).) After exposure to 25 ergs/mm(2), over 70 % of the cells survived for 5 days in culture; moreover, cells which had been stimulated by this dose to incorporate thymidine transformed and divided after exposure to phytohema-glutinin. The final uptake of thymidine was significantly greater when a total dose of 75 ergs/mm(2) was fractionated into three doses of 25 ergs/mm(2) given at six hourly intervals than when it was given as a single dose. The degree of thymidine incorporation and the fraction of leukemic cells labeled were not significantly different from those in normal lymphocytes.