Developmental differences in reaction times under varying conditions.

24 children in Grades 2 and 5 performed a systematically ordered sequence of simple, choice, and precued RT tasks. The younger children's interpretation of instructions differed from that of older children and must be considered in interpreting their RTs.

Determination of 7-dehydrocholesterol in human skin by high-performance liquid chromatography.

A two-stage chromatographic procedure has been devised for the measurement of 7-dehydrocholesterol in human skin. Extracts containing ergosterol as internal standard underwent preparative chromatography on a Spherisorb S5W column using hexane-1% isopropanol as solvent, and an eluted fraction was analysed with an Ultrasphere 5-microns ODS column with methanol-tetrahydrofuran-17.5 mM KH2PO4 (95:1:4, v/v) as solvent and using an amperometric detector at 1.7 V. 7-Dehydrocholesterol could be reliably assayed in human skin samples as small as 5 mm in diameter. In hospital patients skin 7-dehydrocholesterol concentrations ranged from 12 to 81 micrograms/g dry weight.

Audit of opioid prescribing: the effect of hospital guidelines.

The effects of prescribing guidelines for analgesia were assessed by auditing prescriptions for opioids before and after the introduction of hospital prescribing guidelines. Opioid prescriptions were collected by the pharmacy department over a 2-week period in November 1994 and repeated in November 1995. Following the initial audit, analgesic prescribing guidelines were introduced. A statistically significant increase was achieved in the number of prescriptions that were correct for both dose and frequency according to both the British National Formulary recommendations (40-61%; p < 0.001) and our Acute Pain Service guidelines (16-26%; p < 0.05). There was a statistically significant decrease in the number of prescriptions that were inadequate for both dose and frequency according to both the British National Formulary recommendations (18-3%; p < 0.001) and our Acute Pain Service guidelines (36-17%; p = 0.001). The use of accessible prescribing guidelines promotes demonstrable improvements in opioid prescribing.

IL-7 administration alters the CD4:CD8 ratio, increases T cell numbers, and increases T cell function in the absence of activation.

IL-7 is vital for the development of the immune system and profoundly enhances the function of mature T cells. Chronic administration of IL-7 to mice markedly increases T cell numbers, especially CD8(+) T cells, and enhances T cell functional potential. However, the mechanism by which these effects occur remains unclear. This report demonstrates that only 2 days of IL-7 treatment is needed for maximal enhancement of T cell function, as measured by proliferation, with a 6- to 12-fold increase in the proportion of CD4(+) and CD8(+) T cells in cell cycle by 18 h of ex vivo stimulation. Moreover, a 2-day administration of IL-7 in vivo increases basal proliferation by 4- and 14-fold in CD4(+) and CD8(+) T cells, respectively. These effects occur in the absence of cytokine production, increases in most activation markers, and changes in memory markers. This enhanced basal proliferation is the basis for the increase in T cell numbers in that IL-7 induces an additional 60% and 85% of resting CD4(+) and CD8(+) T cells, respectively, to enter cell cycle in mice given IL-7 for 7 days. These results demonstrate that in vivo administration of IL-7 increases T cell numbers and functional potential via a homeostatic, nonactivating process. These findings may suggest a unique clinical niche for IL-7 in that IL-7 therapy may increase T cell numbers and enhance responses to specific antigenic targets while avoiding a general, nonspecific activation of the T cell population.