Assessment and practical science: identifying generalizable characteristics of written assessments that reward and incentivise effective practices in practical science lessons.

High-stakes assessments prominently influence what is done in secondary school science lessons ('washback' effects). It is therefore important that assessments of knowledge and understanding gained from practical work are constructed to reward and incentivise effective practices in practical work. To do that, they must differentiate between pupils who have experienced practical work in different ways. This empirical, mixed-methods study identifies generalizable characteristics of written assessments that differentially reward pupils who experienced practical activities through hands-on work, teacher demonstration, video demonstration, or reading about the activity. Conclusions are drawn from 1486 post-intervention tests completed by pupils aged 14-15 in England, from lesson observations and teacher interviews. This study also identifies pedagogical practices that were more noticeable in practical work that was most rewarded by the written assessments: the work was teacher-guided; and pupils were encouraged to be active participants. Existing literature describes negative washback effects of high-stakes, written assessments that limit the use and effectiveness of practical work as a pedagogical tool. We describe ways in which written assessments could be constructed to better reward effective practices in practical work (practices that better support learning), with the intention of having positive washback effects on pedagogy by better incentivising these practices.

Uric acid promotes tumor immune rejection.

Uric acid released from dying cells has been shown recently to act as a danger signal for the immune system, stimulating dendritic cell maturation and enhancing T-cell responses to foreign antigens. Stimulation of dendritic cell maturation by uric acid has been proposed as a mechanism by which the immune system could generate responses against tumors. We show here that uric acid levels are elevated in tumors undergoing immune rejection and that the inhibition of uric acid production, by systemic administration of allopurinol, or the removal of uric acid, by administration of uricase, delayed tumor immune rejection, whereas subcutaneous administration of crystalline uric acid enhanced the rejection process.

Tumor cell-derived nitric oxide is involved in the immune-rejection of an immunogenic murine lymphoma.

The roles played by host-derived nitric oxide (NO) in the growth and subsequent immune rejection of a immunogenic murine lymphoma were investigated by growing the tumor in mice in which the gene for either inducible NO synthase (iNOS) or endothelial NOS (eNOS) had been ablated. This showed that NO from tumor-infiltrating host cells had no significant effect on either tumor growth or immune rejection, although measurements of tumor nitrite levels and protein nitration showed that there had been significant NO production in the rejected tumors, in both the eNOS and iNOS knockout mice. Inhibition of both tumor and host NOS activities, with an iNOS-selective inhibitor (1400W), a nonselective NOS inhibitor [Nomega-nitro-L-arginine methyl ester (L-NAME)], or scavenging NO with a ruthenium-based scavenger, significantly delayed tumor rejection, while having no appreciable effect on tumor growth. Incubation of tumor cells with medium taken from cultured splenocytes, that had been isolated from immunized animals and activated by incubating them with irradiated tumor cells, resulted in an increase in tumor cell NOS activity and an increase in tumor cell apoptosis, which could be inhibited using L-NAME. We propose that, during the immune rejection of this tumor model, there is induction of tumor NOS activity by cytokines secreted by activated lymphocytes within the tumor and that this results in increased levels of tumor NO that induce tumor cell apoptosis and facilitate immune rejection of the tumor.